"I'm all right," Severus said dismissively, hoping to wave the other boy's concerns away as easily as he waved his hand. "A bit tired, I think. Just then you -- ah -- reminded me of somebody who used to go to school here. But I'm sure it was just a trick of the light. He's been gone from Hogwarts for ages, now." Suddenly, he felt a bit like he was under a Muggle microscope, and unfortunately, buttoning the neck of his robs up again didn't quite help. He wanted to change the subject to ... well, anything but himself, but what was even more unfortunate was that he couldn't think of anything else to say.