Actually, some heat was involved. About two weeks ago, I was on a plane with my MBP. I had closed it and put it away in my backpack expecting it to go into sleep mode. Twenty minutes later, I could feel my backpack getting warm.. and the MBP was 2 pockets away from my back. The heat was going through the Incase cover and 2 layer of nylon in the backpack. When I got on the bus, I took it out and it was smoking hot. I had to slide it out onto the seat next to me. I flipped it over and took the battery out because it was too hot to open. I've gone up to 100C with my computer before, and I am sure it was over 100C on that day.
I wanted to take it to Apple to check it out, but I haven't had time yet. Maybe it's a problem with the temp sensors and/or power controller.