FreeBSD PF and spamd

Awhile after I upgraded to spamd 4.5.0_3 from ports I started seeing this message in /var/log/messages:

Jul 23 15:01:49 host1 spamd[19537]: /sbin/pfctl returned status 1

And this on the console:

pfctl: /dev/fd/8: Is a directory

I was running FreeBSD 7.2-p6 and I upgraded the machine to 8.1 and the problem magically went away.