Don't worry about it. We, as a group of people, tend to see other *Bs when they aren't there. When a diaper advert comes on I look away, not watch it. I would say it was probably nothing. At 10 most kids are more immature than we think - there is a lot of pressure to grow up which means we see ages as more mature than they are often. So that explains liking being held or carried. And there are all sorts of reasons why an advert could catch your attention. Nothing to worry about or get your hopes up about at all.
It can't hurt to watch out for anything, but don't expect anything either, because it probably isn't there. And you definitely shouldn't force it on him or anything. Don't go snooping. There is an off chance he is *B, no more. Don't pay him any more attention than usual or anything, you'll see things that aren't there.