if it happened again its becasue you didn't have it checked for straightness... unless your running a large amount of boost or big back fires its usually the only reason a head gasket goes...
all they need to do is take .003 or so off (what ever gets the bow out of it)
but might i recommend accurately measuring how far the piston is in the hole, and then mill the head for a 9.2:1 compression... makes a world of difference...