>Do you have wm0 in your dhclient.conf?  If so, that will override an 
>interface on the command line, in my experience.  (I'm not sure what 
>happens if there's something in dhclient.leases but not mentioned on 
>the command line.)
>
>
>		--Steve Bellovin, http://www.research.att.com/~smb

thanks! I think that was it.

I've made a new sub-class in my 'site switcher' logic to make sure I don't
inherit wm0 into dhclient.conf.

cheers

-George