Same thing happened to me this morning: https certs signed by lolcat, all dns inquiries not handled by pfsense directly give 195.22.26.248, and using the Google DNS and Level 3 dns servers. I was able to resolve the issue for the time being by checking the 'Allow DNS server list to be overridden by DHCP/PPP on WAN' box, which presumably switched pfsense from using the compromised/poisoned DNS server to my ISPs DNS server.
I originally thought this issue was unrelated to pfsense, and posted the issue here:
https://forum.pfsense.org/index.php?topic=88238.0. But after seeing this thread, it seems like pfsense 2.2 / DNS Resolver / Unbound may be a factor?
Configuration: PFSense 2.2, DNS Resolver, GoogleDNS and Level3 as primary and secondary DNS servers respectively.