I had a similar issue. My grand daughters were playing in the camper and accidentally turned the gas WH switch on without any water in it. I did not notice this until the next afternoon when I happened to walk by and heard the water heater lighting. It apparently had been cycling overnight and into the next day. So far I have not had any problems with it, although it has not been used very much. I hope that the glass lining has not been cracked. I too thought that the high limit switch would have tripped, but it did not. This is a suburban 6 gal, electronic ignition model. Lesson learned.
