Upgrading from PG 8.3.3 to 9.3.4 - FATAL: invalid value for parameter "TimeZone": "PST"

I am posting to both PG and the JDBC group since I am using JDBC to
connect, so I'm not sure if this is a PG issue or a PG JDBC issue.

I am upgrading from 8.3.3 to 9.3.4. I ran pg_dump on my 8.3.3 databases
(which ran on CentOS 5.2, Java 6) and ran pg_restore on my 9.3.4
databases (which runs on CentOS 6.4, Java 7.0.55, using JDBC
postgresql-9.3-1101.jdbc41.jar). The new databases appear to be correct
in that I can run psql and query my tables and I don't see any obvious
issues.

In fact, I seem to be able to run several applications at the same time,
each connecting to its own database.

But I also see that sometimes I get this error in my postgresql.log file:

FATAL: invalid value for parameter "TimeZone": "PST"

I normally run about 35-40 webapps at a time in our dev environment
without issue, but when I try to start them all, it seems this error
occurs on nearly every application. Yet when I only run about 10, I
don't seem to see the issue at all. I have tried adding them in one at
a time to see if there was a "rogue" webapp, but when I find a newly
added one suffers the TimeZone FATAL error above, if I restart Tomcat,
it may then be fine. Apps that run okay at one time, will exhibit the
error when I try to add the others in.

Does anybody have any ideas on what I might try? I did a 'yum update'
to get the latest, rebooted, recompiled PG and reloaded the DBs, but
that made no difference.

Thanks for any tips if anybody has seen this!

David