No, you weren't over reacting. I am guessing they did nothing? Might have been better to just tell the fa verbally so she could check it out herself. She probably didn't think it was serious. It probably wasn't since it sounds like nothing happened, but it should have been checked out by an fa or an off duty pilot if one was riding in back. If it was too hot to touch and there was any electrical smoke or smell, a divert might be warranted depending on a number of factors (weather, distance to destination, etc) I would always rather have somebody say something so I check it out to see whether it is something to worry about or not.