Same thing happened to me earlier this morning. I woke up to being burned on my back because I charge my iPhone 4 on the bed with me when I sleep. When I rolled over in the morning, and I rolled on top of my extremely hot iPhone and I quickly jumped out of bed and unplugged it. I don't know how it got so hot or why, I think it just overcharged alot, but I still don't know if it was the cord/charger, or the phone itself. When I turned on the light and saw how melted the cord was, I was concerned and relieved that that I found it when I did and the house didn't burn down. My iPhone surprisingly and Luckly still works, but I don't know if I should return it.