Timezones dont matter here.
I believe internally, Hyperic stores all timestamps in UTC format.
In that offset column, if you see values greater than 1 min (60000 ms), then you should be worried.
I try to keep them under 500ms. Anything greater than that is an indication that something is/or is about to go wrong.
More info can be found in official Hyperic documentation - http://pubs.vmware.com/vfabric5/index.jsp?topic=/com.vmware.vfabric.hyperic.4.6/Troubleshoot_Agent_and_Server_Problems.html
One more thing - as per my observations, windows servers (especially Win 2003) tend to have greater offsets.
Installing and configuring NTP/Win Time Service usually solves all time-sync problems.
Here is a sample of offset values you should see -
