I'm pretty sure you answered your own question. He has claimed you. Just that once in awhile one of the other dogs dares to display some signal that is subtle enough that you don't notice it, a signal that they are going to make a move towards mom or something of that nature and it sets him off.
Actually, you're lucky he hasn't marked you. I've heard of plenty of male dogs and cats doing that to their owners if they are not neutered. True love!
