another idea -- even though most twelve year olds would be absolutely mortified to admit this, severe or recurring nightmares are not THAT uncommon. if it happened at night, maybe he had to urinate after a nightmare and was too scared to get out of bed? i know approaching it could be embarrasing since he'll probably look at you like "WHAT? NO WAY!" but i think it's worth asking. after a traumatic event in my life just over a year ago, as an adult woman, i had nightmares so bad there were several occasions i was too scared to get out of bed for ANYTHING. i never urinated in or around my bed but if i had to pee during one of those episodes following a nightmare, i just might have considered it.
