Is it normal that i like the smell of my gf ass

When Im fucking my girl from behind and her ass is spread I cant help but stare at her perfect asshole. I then eat her out from behind where my nose is right in her asshole. It smells good to me and make my dick twitch. There's just a faint smell of sweat because her htygiene is so good. Sometimes if she just got out of the shower ill lick it to. Is it normal that I like her ass smell?