Snape rose to his feet to greet his guest, inclining his head in a courtly nod. "Not at all, Madam Malfoy," he murmured, "It's always a pleasure to see you. Would you care for some refreshments?" A house elf popped in, waiting in the doorway with goggle-eyed eagerness for orders.
Snape re-seated himself when it was polite to do so, fixing Astoria with an interested look and asking "If I may be so bold, what brings you here today?"