Picked up my 3rd Replacement (4th) iPod today, and it seems like it's heating up pretty fast. I can play 15 or so minutes of Stardunk or Archtype (both online games) and my iPod gets hot enough to make my hand sweat. I closed out of all my multitasking apps, but it doesn't seem to have an effect. It heats up on the back towards the top (by the camera). Is this a common issue or what?