Is it normal my girlfriend and i judge other people's attractiveness?

My girlfriend and I like to go out in public and judge other people's attractiveness. We could see them anywhere, on the street, in a store, a mall, or other public location. We talk to each other about if we find random strangers attractive that we see out in public and if we would consider having sex with them. This has made our relationship stronger, being able to openly share our feelings.