He meets that confused expression with a confused look of his own. It takes him a moment to even formulate what to say, and even then he ends up just stating, bluntly, "You're crying?"

If Seth says he's fine, then that's fine with him. But the fact he doesn't even seem to realize he's crying is alarming to him, perhaps even more so then the kid beginning to cry from a hug in the first place. What a whirlwind this kid has taken him on.