Had a search around the forums but couldn't really find any definitive answers on this. When I use my iPhone, particularly when browsing or watching a video, it has a tendency to heat up over time. Not to the point at which it's uncomfortable to hold it or anything, but it does get very warm on the back. My concern is that it may get worse in time or it may have an impact on the phone's function - for example it might affect the battery life. Has anyone else found this? Is this normal or is it worth getting it checked out at the store?