[She's fighting a tiny war with herself that possibly no one else notices. How much is too much public information where Reid could be seeing it and how much is too little where Chekov might feel like her dirty little secret? She doesn't want to hurt either of them.]
We didn't do things that night. We haven't. I just wanted to be ready if we wanted to eventually. [And then there are some things she tells Jack because he's Jack, but those should definitely be private.]