Default Battery 'overheating'...

My battery's telling me it's overheating.... Sometimes. It happened quite a while ago, and it's happening now. I know it isn't, because the battery is operating at 15c.... Also, it only happens with the 4800mAh extended battery, and it's ONLY happened since I updated to 2.4.4.... So, I don't know which one is causing the problem. Also, this only happens when I'm charging using a USB-wall outlet adapter.