Postmaster uses Large Amounts of Swap

Today I noticed that the swap used on my system was > 120M, and it seems
to be coming from the postmaster:

USER %CPU %MEM VSZ RSS STAT START TIME COMMAND
postgres 0.0 0.0 1668 0 SW 2000 0:00 [pg_ctl]
postgres 0.1 1.1 135840 1528 S 2000 134:56 /usr/bin/postmaster -i

That's not normal, is it?

It's been running for 73 days, with fairly light load: there's only one
small database with five tables, all under 2,000 rows, and it gets on
average about one select query every ten seconds and one update query a
minute. I vacuum it about once a week.

The database itself appears to work just fine.

I don't know how long it's been like that; I would think I would have
noticed before this if it had been like that for a while, but I can't
promise that's the case. I've been watching it for two hours and the
amount of memory used has not changed.

I could just restart it and see if it happens again, but I'm wondering if
(assuming this is an aberration) there is something I should check to
find out more details before killing it.

I'm using version 7.0.2 installed from i386 RPMs on Red Hat Linux 6.2.
The machine has 128M of RAM (of which only 55M is in use by other
processes) and 256M of swap.

--
Robert L Mathews, Tiger Technologies