Yo I have this exact same thing with my (25m) girlfriend (25f) in a 2 year relationship. She'll point things like that out and it makes me feel icky and uncomfortable. She'll also bring up things about past hookups (like funny stories) and that is even worse. That said, she is a wonderful girl and makes me very happy in general.

When she says stuff like that it is right on the edge of making me uncomfortable enough to bring it up, so after a while I did. I basically said I appreciate that she's realistic and doesn't pretend like I'm the only person in the world she finds attractive, but hearing about it makes me feel weird and overthink things that I was totally secure about before she said anything.

She was cool about it and I realized she's such a secure person that if I was to say someone is attractive she wouldn't be bothered by it even a tiny bit. It just didn't occur to her that it would make me feel bad, and once we talked about it she had been much more mindful of it. I think it's worth bringing up in as non accusatory a way as possible :)