Only reference I've found to a similar issue is

All emails and appointments in webaccess are showing as 1 hour earlier than actual, the groupwise client however is fine. Server OS timezone is set correctly as far as I can tell. Is there something I can check or is this likely a bug?

We are running 2012 SP1, exact version as listed in webaccess is
Build Number: 103731
Program Release: 12.0.1 9/6/2012