"It's a habit I thought I'd grown out of," he said, with a note of relief. He found her smile disarming; he smiled back, briefly entertaining memories of the little corner of the library into which he'd practically barricaded himself during his seventh year. Somewhere near the Arithmancy stacks, he thought. "Apparently not. Do you - work there?" He was quite certain she wasn't a student, and there were few other legitimate reasons to be caught by the Hogwarts librarian. She seemed young for the faculty, but then, there were professors his age, now. She hadn't been in his class; he couldn't place her, and he was pretty sure he'd have remembered. "I suppose I'm not surprised that graduation is no shield against Madame Pince."