I accidentally placed my iPad in my backpack next to a frozen dinner I planned to have for lunch, then forgot my bag in the car. By the time I got back to pick it up a couple hours later, the iPad, in it's Apple case, was cold to the touch. When I tried to power it on the screen was extremely dim and barely visible. I crossed my fingers, left it out of the bag for a few hours, and when I returned it was at normal temperature and worked just fine. Is that a common occurrence, and if so... why?