Downlevel database

We have a problem with a PosgreSQL database where the user cannot get
to their tables any more. I am not the primary administrator of this
host (who is on vacation), nor am I the user of this database. The
/var/log/posgresql file has entries like the following, at the end:

FATAL 1: Database "trees_rock" does not exist in the system catalog.

The current running version of the database is 7.2.2, and I suspect the
database was created and maintained with 7.3.4 (after examining the
bash history file for user postgres).

Would running downlevel software cause this problem? Does this seem
likely or possible? Now that the old database software is running on
the new data, what do I do to recover?

--
Gary Jackson
bargle(at)umiacs(dot)umd(dot)edu