His eyebrow arched even further when he realized she'd just had her hand on the hilt of a sword. Interesting. And, upon closer inspection, scant or not, her outfit appeared to be armored. The lack of cover, then, likely made for better movement, though it seemed a bit impractical to him to leave so much skin unarmored. Then again, he fought with spells and not a sword, so what did he know?
"Severus Snape," he answered with a nod that thankfully didn't hurt at all, when compared to the day before, and he extended his hand to shake hers. Then he nodded again at her question. "Just yesterday, in fact," he said with a wry smile, folding his arms over his chest.
Apparently this Xena hadn't seem him around before, even if Lily might have thought she had. Then again, perhaps seeing Lily the day before had only been a pleasant dream. Granted, the cauldron and ingredients for Wolfsbane were still in his room when he woke ... but that didn't mean it had to have been Lily who gave them to him, did it?