Only 5 days into 2014 and I think I've won the stupidity award already!
Had to do some work on the bedroom slide so stood the mattress (heavy Spring Air) up at the foot of the bed. After about an hour I went to my neighbor's place to see if he had a very small bottle jack (didn't). Came back and the smoke alarm was going off in the bedroom. I smelled something but didn't smell like smoke so opened the doors and turned on the exhaust fans. Then I looked up and saw the mattress smoking. I had wedged it against a halogen puck light. Pulled the mattress away from the ceiling and it really began to smoke. I manhandled the mattress to get the smoking side against the floor as I didn't want it to flame up against the ceiling and drug it our of the coach. As soon as I had it outside it ignited in flames. Only damage to coach was a singed ceiling panel, which I can re-upholster and a couple of burn spots in the carpet where I had to stop dragging it to get a better grip. I plan to replace teh flooring anyway so no loss here.
I'd replaced the halogens with LEDs everywhere but the bedroom (Murphy's Law). Despite using copious amounts of water on the mattress, it reignited twice over about a 3 hour period after being outside. BTW, smoldering mattress (latex, etc.) has a unique smell.
Stupid mistake but someone must have been watching out for me........
Steve