Lisa had frowned at the realization that there had been something there for the girl to scourgify. Gross! To say she was glad she'd run into the Gryffindor at that point was an understatement. She was definitely grateful.
"Thank you," she said with a smile and she turned. "I'm Lisa Turpin, by the way, I don't think we've formerly met." She extended her hand to the girl for politeness sake.