My 2010 Corolla (now in summer season) is making a popping sound in the roof. I will just be driving in normal conditions and it sounds like something dropped on top of the car. The roof metal is starting to look like it has some large wrinkles in it (front, middle area). There is no sunroof, so that is not an issue. Just wondering if there is metal fatigue with this car. I have had this car in the garage a lot, leaving outside more recently. Thanks.