DHCP client and PF rules

[RW]

My desktop PC get its IP address from a PPPoA modem connected with ethernet. I 
started logging DHCP in PF, to make sure I wasn't dropping anything, but the 
*only* packets  I'm seeing are incoming broadcast:

    pass in on vr0: 10.0.0.2.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, 
    length: 548

I presume that the DHCP client is bypassing the firewall, but I'm wondering 
about these incoming  broadcast packets - whether they have already been seen 
(and can be dropped) or not. The sessions are renewing without any specific 
DHCP rules.