Casual as it might look, there's still a note of defensiveness around her posture. It's a natural reaction when Carlisle is, essentially, glaring daggers at her. Still, she doesn't see why she should apologise for taking action, for trying to find out more about something which sounded like the only option at the time.

"In case you started babblin' all over the network." Obviously. Not that she had thought so deeply about it at the time, just decided that something needed doing and soon. And that she didn't want Carlisle to know. Maybe he's right, but--

Well, she's stubborn, and as defensive as the position of her arms is.