To be fair, he didn't expect to see himself here, either. He can understand the sentiment: holiday festivities were thrust on one very much in the same way as responsibility. First Albus, now Martha. And speaking of Martha, he glances around and makes an accusatory, albeit vague, gesture in her direction. Much as he feels he doesn't owe Granger an explanation, neither does he want to put her off entirely. Or be blamed for the decision to come.

"It is fortuitous, I suppose." He doesn't sound like it's fortuitous. To Severus, this is just another headache in the settling-in process. Making nice with the locals. And with that, he gives Hermione the full focus of his attention. "A word?"

She doesn't appear to be doing anything of importance (insofar as reading is unimportant), and it isn't a request so much as a 'Get up, I want to talk to you privately.' with some room for argument.