Lily's sorting when he arrives. She's always sorting, or bottling, or labeling, or brewing, or something - she never stops working if left to her own devices, that Lily Evans. So it's probably good that the expected-unexpected visit gives her enough pause to stop and smile, putting a hand on her hip as she straightens up to look at him.

"I've plenty of moments for you, Horace." It's still strange to call one's professor by their first name, but when one is graduated, well. It becomes second nature. "What can I do for you today?"

(Horace Slughorn, one of the few people that sees her full potential, is worth her full attention as well.)