She is less worried about the propriety of it all and more annoyed at the way she keeps falling asleep despite herself -- how is she supposed to get anything done, like this? She's very little use to Her Majesty or anyone if she's sleeping away the time she should be spending working.
The annoyance doesn't stop her from aiming a small, grateful smile at Sebastian as she leans in to take the cup, breathe in the scent of the tea, letting it calm her just a little.
"That is not what I was concerned about... mostly, at least. I was dreaming about home. About something that happened -- it was not a nice memory. I doubt anyone really appreciates suddenly falling asleep and finding themselves in the dungeons," she sighs.