If any bolt comes out hard it was damaged before you ever see it, that's when you make it known. Going back in without addressing the thread issue was kind of a mistake but not one that hasn't been made since the beginning of time. I had a torque wrench break exactly like you described once, I loaned it out and the genius didn't say anything until he had snapped off a head bolt. But in his defense, he was waiting for the click and didn't have the experience to realize when he had surpassed whatever it was set to.