I've got gaps in the log files?

Hi,
it appeares I've got gaps in the log files.

It's a PG 9.1 from the OpenSuse 12.1 distribution.

I know the server is running so it should dump it's feelings all the
time in those files in PGDATA/pg_log.
But I find huge gaps where nothing is written.

E.g. yesterday the last entry is at 09.54pm. Thats the change timestamp
of the file, too.

Today there is a new file whichs first line is 11.37am while I
definitely know there were users connected way earlier and there should
be comlaints about lost connections all the time as it is "normal" with
MS-Access as client via odbc.

Actually I was working at it yesterday after 10pm so there should be
log-lines for my DDL queries from that timespan.

OK, my issue might sound weired but I'd rather like to know where this
log stuff could have gotten lost.