What could cause postmaster to be started many times?

I ran into a situation where (without any known changes) a simple login
script would fail ("sorry buddy, session headers already sent") and each
time it seemed a new postmaster would be started. ps -aux showed about
8+ processes this morning but I find that hard to believe because the
sandbox machine only has 256 MB RAM and load was low (in my haste, I did
not note all information). There are no scripts that can start the
postmaster. I just use /usr/local/pgsql/bin/postmaster -S -i -D
/usr/local/pgsql/data. I am not sure of the cause and effect, or how
things got better.

What could cause this kind of behavior and how might I avoid it in the
future? Any clues?

PG 7.0.3 on FreeBDS 4.1 and  php 4.0.4pl1. There were no extra
.s.PGSQL.5432 sockets.

Thanks, Jeff