Exact same thing happened to me a few months ago
I was taking a snake out of her cage, set the 150 watt heat lamp (on a timer, turned off about an hour before this happened) on the floor to get the lid off, put her back, and forgot to put the lamp back on top. The next morning I woke up to a funny smell and the smoke detecter going nuts. The timer had turned the light back on while sitting on the rug on the hardwood floor.
Now theres a burn mark about the size of a saucer on the floor. The rug
did look pretty awesome though lol...like it was hit by a cannonball
Not gonna do that again...