[Once she's finished hanging out with Ciel in the office and exits into the opulence that's supposed to be their modest waiting hall, she'll find Sebastian busy with re-filling the refreshments table. He looks up at her with a calm little smile when she opens the office door.]
Ah, Your Highness. [He talked to Kija for more than five minutes when he was here; it was inevitable.] I did think I heard your voice.
[It doesn't show in his expression, but he's slightly annoyed at himself to be caught doing these little re-touches. A servant is neither heard not seen, after all; only the effects of his work are.]