Re: Open
Noting the Doctor's expression, Sally decided two things. One, she probably shouldn't show that key to anyone else, at all, until she returned it safely to its owner. Two, she needed to do some rapid talking before this Doctor decided to take the key himself.
"Look, you said there were alternate versions of you around. I'm just figuring out that whole concept, and I met a woman yesterday who seems to have run into several versions of her husband who aren't human. She seems fairly sure her version is, and I had no way of knowing how different all the versions of you were. I didn't think it was safe to assume anything."
She paused for breath, having rushed that out a little, then added "I should have known you'd worry about someone you didn't know having this. I know perfectly well just how bad things could be if it fell into the wrong hands."