Yes, i have the same feeling, 2-3 versions before my battery lasted for 2 days with normal daily useage, now lasts for 1. Without sim card there is hardly any battery drain, so I have already started to thinking of to change the sim but why it was much better before? I dont want to root it, but that shoud be the way to see what is happening underneath by installing a monitoring application because without it i can see only the surface but that is not proper information. And yes, no overheating or anything, and my battery is ~6month old