geezer: you're right its not worth the risk to keep that regulator attached, with 2000psi surging through it can go bad really quick. I shut the gas and took that thing right off after I found out where the gas was leaking from.

jakeru: looks like the shop might have installed the new nipple that was too big for the opening and caused it to expand and crack. Or another possibility was that they heated the nipple to try to remove it from the regulator which caused the metal to become brittle. But that is just my guess. If its cracked its best to replace.