I'm not sure if he'd really know her. Perhaps she attends a few of his parties, and maybe tried flirting with him a bit. But Hahn's not the type to pay a lot of attention to the girls that just flirt with him. He might remember her from Quidditch or something, but that's not his main focus. I don't really think he'd have much of a connection to her, but she might know who he is.