How bad is it to find other girls hotter than my girlfriend?

My girlfriend is my first relationship I've been in, we've been dating for a little over 3 months now. 23M/24F.

To be clear, I find her very attractive, but that's only a secondary reason to why I'm dating her. She also shares a lot of the same values as me, she's super kind and sweet, and in all the ways that—to me at least—are more important than physical attraction, she's awesome, and we're honestly a great couple.

That said, there have been times when I have caught myself noticing that some other girl is hot, not in a staring, creepy way, just a quick glance, the same way I would find someone hot when I was single. I always feel guilty for this, because I love my girlfriend more than almost anyone, and don't want to leave her, but I don't know how to just turn off my sexuality towards everyone else.

Is this something that is normal? I also don't know if I should bring this up with her, since I don't want her to get the impression that I don't love her, or that I'm having second thoughts, because that's not what it is.