Pence was ignoring him in order to hug all the little girls. Even when the kid finally got his attention, he barely touched him on the head and while saying "I'm sorry I bopped you" was already turning away to gush over yet another little girl.
I'm not saying he's a pedophile. I'm saying that it is ingrained in his behavior to think of females as there to be hugged. They're so cute, after all. He doesn't want to actually have a conversation with a child.....they don't even vote, for heavens' sakes. Just hug the cute ones, for the photo op.