"What's so different about it?" Short of this 'thing about humans', which he still doesn't quite follow.

"He's been in the carnival for a while. I would assume that anyone who spends enough time here would become accustomed to magic." He gestures again, vaguely, with the empty shot glass. "We are absolutely saturated in it."

Enough that it's altering their physical body, which will always be a little unsettling for someone who's much more used to having greater control of his appearance. Not so completely disturbed to regret this, but... he's seen some of the other carnival members.