A poor tale... He let the talk of Arya's sister fall to the side for now. There was something more pressing.

"All I said about her saying those names. You can't tell anyone. It can't be in the letter."

The Boltons were traitors that served the Lannisters now. If they found out Arya's treachery, he could only guess what they might do. After all, she was married to a bastard now.