Postgres has stopped logging

This is a really strange one.  We are running PostgreSQL 8.3.7 on a
Fedora Core 8 system (uname -a gives: 2.6.23.1-42.fc8).

On Wednesday I was reading about the upcoming change in the default
value of default_statistics_target from 10 to 100 - we had never changed
this value, so I bumped it up a bit and also changed the value of
log_autovacuum_min_duration so that I could monitor the results.
Yesterday I tweaked the settings a bit more and continued to monitor the
logs.  About two hours later, the log file stopped growing.

At first I didn't fully realize what had happened, I thought there was
just low activity.  Today I checked again and realized there had been no
logs since yesterday afternoon.  I made another minor adjustment to the
config file and issued pg_ctl reload, to see if I could force something
to show up in the log - nothing.  The time stamp on the latest log file
is still from yesterday.

The log location is under the /var partition, the df command shows usage
at 3%, so this is not being caused by a full partition.  I am baffled as
to what I can try next, other than a server restart, which I am
reluctant to do since this is a production server.

The server is working normally, as far as I can tell, apart from this.

I would be most grateful if anyone can suggest the next step for
troubleshooting this issue.

Thank you.

Lewis Kapell