A split-second before he spots the kitten she frowns, having felt it pop into existence made up of her own atmosphere. Things just manifesting inside her without her knowledge or doing is quite disconcerting and usually a sign of something with great power trying to interfere with them, so she is immediately on guard even as she's still surprised. With some delay, she moves her physical form to stare at the kitten and the Doctor scooping it into his arms.

She doesn't even notice that his words make it sound like he's familiar with the apparition (she can already tell as much, it's certainly not a real cat), as she's too busy analyzing it, and... Once more she frowns in incomprehension. "It is connected to you."