Possession is 9/10ths?

We went to a birthday party this morning, and as often, there was a gift bag. Jamie is very into these and immediately looks in to assess the take. Upon seeing a matchbox car in his bag, he moved quickly to get into Connor's bag to compare cars and see which he preferred. Connor had a sort of pimped-out pickup truck which they both came to like. They were "sharing" it for a while but when we got home Connor saw it in Jamie's hand and started screaming for it, so Jamie had to settle for his own car. Connor took the truck up with him for a nap and was unwilling to relinquish it. When I came down Jamie asked "Did you get my truck back from Connor?" "No," I said, "and besides it's not your truck, it's Connor's." "No," he replied innocently, "it's mine. I took it out of his bag!"