Maybe I overinflated it?
Difficult to see how this could happen on a self inflating mattress. I would suggest that maybe one of the caps wasnt on correctly or possibly even faulty. They are however susceptible to holes as any air bed is. When tenting it, we use an old sofa bed mattress that is sufficient for a few nights at a time. This is depending on your own comfort levels of course. If you check out a rubber and foam supplier, you may even find a material that is suitable without the risk of a puncture.
Please sir, Can I have some more? Time off that is.
"Hard at it"
Fruit Bat Falls, Cape York