Every so often (rare now, but often when I first got it) my Galaxy S2 is found, after operating but left in my pocket, screen off, with the battery very hot, and almost run out. I have searched the net, but the answers seem to focus on buttons being pressed simultaneously. however, I blank the screen manually after each use. What is causing the isue, and how do I solve it. It doesn't appear to have happened for the past year (just a guess at the time frame). It's in an Otter case.