Are you sure there's a crack or is the head gasket leaking? Improper torque and a head that hasn't been lapped can contribute to head leakage. Also the chrome acorn nuts might be your problem if you're using them.
It isn't unheard of; I've seen a brand new cylinder head that had a crack up through the spark plug threads but I'd need to see where you suspect your cylinder head is cracked.
Any close up photos?