ipfw in daily security run

I get the following in my daily security run email:

---
fbsd.local pf denied packets:
+++ /tmp/security.3Nfo4MZX        Tue Sep 20 03:06:03 2005
+block drop in log quick on xl0 inet proto tcp from x.x.0.0/16 to (xl0) [
Evaluations: 8137348 Packets: 0 Bytes: 0 States: 0 ]
...
ipfw: getsockopt(IP_FW_GET): Protocol not available
---

My question is, why is ipfw in the pf denied packets log? As the message
suggests, i do not use ipfw or have it compiled in to the kernel.

Thanks.