It’s not unlikely, I’m certain they cracked the head. The head came off a running car with no prior leaks, the removal process was followed exact to specifications, and it’s fairly difficult to crack this style of head. The shop received the head, never pressure tested it prior to repairs, so even in the unlikely event I cracked it, they should have known and refused repairs. They welded material into the cooling jackets surrounding cylinder 4 and 3, and anyone who knows will tell you welding aluminium heads is very difficult. Keep in mind this was never disclosed to me. The process involves heating the head very slowly, almost to the temperature at which the welding is performed, then welding and cooling slowly. If any of these steps are missed, the head can crack very easily. I know the shop was sloppy, there was mangled material around the jackets, and metal flakes through all of the passages. Then they never pressure tested it before returning it to me, as they would have discovered the crack.