[Having been meticulously careful about keeping Sebastian's origination a secret for so many years, Ciel's not stupid enough to just come out and say it. So no, this charade's going to continue, at least until she outright says the word "demon" to him.]
And now you're complimenting me. Will today's surprises ever cease to exist. [Gestures vaguely.] I assure you, him providing me a night cap is, what was it you said earlier? Just a different standard from a different culture for propriety.