It was revealed very early on that she's a gravure idol, but this really hammers home that point. So far we got to see only the ordinary high school girl side of her, but here we see her being a bonafide gravure idol who's actually known by people.
I suppose it's kind of unsettling for him to be reminded that they're not exactly equals in this, which might play a role in why he's being so distant when it comes to trying out romance with her (and everything else that comes after). She's got a name for herself and here's a side of her that many people have seen, but she hasn't shown to him up until this point.