With Amy's knowledge of the Doctor being so closely tied to what she knew of the version she travelled with, she would have to take a guess that he'd always been so skittish when it came to certain things. Like when he flailed about when she went about attempting to try it on with him after what happened with the Weeping Angels, acting like he was some sort of awkward teenager. So if she were to find out that it really was like that for other versions of him, at least in arriving in a women's changing room, she'd have to laugh a little as that wouldn't be a surprise.
When this man calling himself the Doctor began to circle around her, she looked at him with a little bit of an indignant look, followed with a "Hey!", because if anyone was going to be circling anyone here, it was her.
"I travel with the Doctor, but he's all bow ties and tweed and ridiculous hair. Then there's this bloke on the network for this place who called himself the Doctor, too." A beat quickly passed, before she added, "And no, I haven't met you before."