It shouldn't be warped unless it blew because it got really hot.
I say head gasket as well. It shouldn't be warped unless it blew because it got really hot. Kinda sux since you just had it rebuilt not long ago, but while you're in there, might as well put a new timing belt unless you want to tear it down again in 20,000 mi. (I'm just lazy like that.) Some good head studs wouldn't hurt either, expecially if they are still the stock ones.
DSMparts.com is running a specail on an ARP headgasket and studs for like $180 if you are interested:
ARP DSM HeadStuds + 4 Layer DSM Metal HeadgasketRan accross that while pricing kevlar timing belts.