Head gaskets have been a wear item especially since the advent of aluminum heads and cast iron blocks. The head is creeping with expansion and contraction to one degree or another all the time in comparison to the block. Your engine may have cast iron heads as i am not familar with it though. This does not make it trouble free but certainly better. Gasket manufactures try to refine their products on an almost constant basis. A lot of head bolts are stretch one time use devices as well. As for the guys integrety just have a look yourself. You may have to clean up the leak area a little to inspect. Or get a second opinion.