Hi,
I have a strange problem with the change of sessions, when I'm sending email from my android 2.3.3 (SGS+) and at the same time I'm logged in to Zimbra webmail:
My configuration below:

Centos 5.6
z-push-1.5.5-790
zimbraBackend51.4
PHP version: 5.3.8
Zimbra Release 6.0.14_GA_2928.RHEL5_64_20110802123437 CentOS5_64 FOSS edition

Everything is working correctly: I can sync my mails, calendars, contacts, et.
The problem is, when I send mails from a mobile, I noticed "session id changed" in debug.txt quite often:

11/09/11 19:39:38 [29955] [l@domain.com] Session Id changed - OLD [15932] -> NEW [15940]
11/09/11 19:39:38 [29955] [l@domain.com] Found 0 message changes
11/09/11 19:39:38 [29955] [l@domain.com] Initializing message diff engine
11/09/11 19:39:38 [29955] [l@domain.com] 1 messages in state
11/09/11 19:39:38 [29955] [l@domain.com] Found 0 message changes
11/09/11 19:39:38 [29955] [l@domain.com] Initializing message diff engine
11/09/11 19:39:38 [29955] [l@domain.com] 1 messages in state
11/09/11 19:39:38 [29955] [l@domain.com] Found 0 message changes
11/09/11 19:39:38 [29959] [l@domain.com] Initializing message diff engine
11/09/11 19:39:38 [29959] [l@domain.com] 1 messages in state
11/09/11 19:39:38 [29959] [l@domain.com] Send SyncRequest
11/09/11 19:39:38 [29959] [l@domain.com] Session Id changed - OLD [15935] -> NEW [15941]
11/09/11 19:39:38 [29959] [l@domain.com] Found 0 message changes
11/09/11 19:39:38 [29959] [l@domain.com] Initializing message diff engine
11/09/11 19:39:38 [29959] [l@domain.com] 1 messages in state
11/09/11 19:39:38 [29959] [l@domain.com] Found 0 message changes
11/09/11 19:39:38 [29959] [l@domain.com] Initializing message diff engine
11/09/11 19:39:38 [29959] [l@domain.com] 1 messages in state
11/09/11 19:39:38 [29959] [l@domain.com] Found 0 message changes
11/09/11 19:39:40 [29938] [l@domain.com] Initializing message diff engine
11/09/11 19:39:40 [29938] [l@domain.com] 1 messages in state
11/09/11 19:39:40 [29938] [l@domain.com] Send SyncRequest
11/09/11 19:39:40 [29938] [l@domain.com] Session Id changed - OLD [15936] -> NEW [15942]
11/09/11 19:39:40 [29938] [l@domain.com] Found 0 message changes
11/09/11 19:39:40 [29938] [l@domain.com] Initializing message diff engine
11/09/11 19:39:40 [29938] [l@domain.com] 1 messages in state
11/09/11 19:39:40 [29938] [l@domain.com] Found 0 message changes
11/09/11 19:39:40 [29938] [l@domain.com] Initializing message diff engine
11/09/11 19:39:40 [29938] [l@domain.com] 1 messages in state
11/09/11 19:39:40 [29938] [l@domain.com] Found 0 message changes
11/09/11 19:39:41 [29943] [l@domain.com] Initializing message diff engine
11/09/11 19:39:41 [29943] [l@domain.com] 1 messages in state
11/09/11 19:39:41 [29943] [l@domain.com] Send SyncRequest
11/09/11 19:39:41 [29943] [l@domain.com] Session Id changed - OLD [15937] -> NEW [15943]
11/09/11 19:39:42 [29949] [l@domain.com] Session Id changed - OLD [15938] -> NEW [15944]
...
11/09/11 19:39:42 [29924] [l@domain.com] Session Id changed - OLD [15939] -> NEW [15945]
....
11/09/11 19:39:43 [29955] [l@domain.com] Session Id changed - OLD [15940] -> NEW [15946]
...
11/09/11 19:39:43 [29959] [l@domain.com] Session Id changed - OLD [15941] -> NEW [15947]

...
11/09/11 19:39:45 [29938] [l@domain.com] Session Id changed - OLD [15942] -> NEW [15948]
...
and so on...

At the same time I noticed this in mailbox.log from zimbra server:

2011-11-09 19:39:35,514 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:35,515 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15933
2011-11-09 19:39:36,190 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:36,191 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15934
2011-11-09 19:39:37,031 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:37,032 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15930
2011-11-09 19:39:37,129 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:37,129 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15931
2011-11-09 19:39:38,048 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:38,048 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15932
2011-11-09 19:39:38,659 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:38,659 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15935
2011-11-09 19:39:40,536 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:40,537 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15936
2011-11-09 19:39:41,212 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:41,213 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15937
2011-11-09 19:39:42,054 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:42,054 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15938
2011-11-09 19:39:42,151 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:42,151 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15939
2011-11-09 19:39:43,071 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:43,071 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15940
2011-11-09 19:39:43,071 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15940
2011-11-09 19:39:43,679 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:43,680 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15941
2011-11-09 19:39:45,559 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:45,560 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15942
2011-11-09 19:39:46,234 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:46,234 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15943
2011-11-09 19:39:47,076 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:47,121 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15944
2011-11-09 19:39:47,173 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:47,173 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15945
2011-11-09 19:39:48,092 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:48,092 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15946
2011-11-09 19:39:48,701 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] soap - SyncRequest
2011-11-09 19:39:48,701 INFO [btpool0-73://zimbra.domain.com/service/soap] [name=l@domain.com;mid=5;ip=10.0.0.3;] session - requested session no longer exists: 15947
...........

(10.0.0.3 is the internal Apache server where z-push is installed and it is separate server.)

There would be nothing wrong with that, because I have full functionality, but problem arises when I'm logged in to Zimbra web and my phone is connected to zpush on the same account at the same time, then I "feel" double SOAP requests in browser: clicking on one of the mail execute another requests (my mouse pointer is busy "twice" , not once as before). Finally, my zimbra webmail jumps me to the first thread/mail in my Inbox. It's a bit tedious.

Has anyone encountered a similar problem?
The temporary fix is to restart httpd on the z-push server, but after a while the problem occurs again.
When I'm using 5 minutes interval for syncing (not push), there is no problem.
Please help.