Come in, why don't you. He doesn't say it, because Malfoy. It's almost a charming character quirk, by now. Severus closes the door once he's inside and meanders, unhurried.

"I can actually offer you a drink if you're inclined," courtesy of Dolohov, "otherwise we can sit down and go over it."

He is judging the weight of this errand on the fact that Lucius showed up in person, at all, and not his claim that whatever it is won't keep him. It's been an odd week; Severus isn't about to discount anything.