Is it normal that i think my friend is hot?

I'm a straight girl. I know I'm not a lesbian or bisexual because I can't imagine myself in a relationship with another woman... that's just not for me. However, I have a friend (and I've had this feeling towards other women in the past) who just seems really hot to me. I think it's because she gives off this really sexy vibe, even though she dresses and acts really modest... and she's touched my nipples and kissed my boobs before and I've made out with her at a party once... and it was no big deal. Her boyfriend always thought it was really hot that we did it, sometimes telling us that we should do it more often. I've only had this feeling towards confident, powerful women... especially ones that just radiate sexuality (which she does). I have no idea why... but it's kind of sexy to me.
Also, I don't think I would have a problem with going down on her or anything, or her on me... I've even thought of a 3-way with her and her boyfriend before, but of course I'd never bring that up. I don't know if I could ever act on these impulses, but I think about it a lot.