tight feeling in chest when thinking about hookup??

the other night i hooked up with my really close guy friend. we didn’t go far at all because it was a party and our friends were in the room next to us, so we just made out like pretty intensely. i thought it would be weird because were such good friends but it wasn’t which is good, but now when i think about it i get this like tight feeling in my chest like i can’t move but i don’t know why because it was really good and i don’t regret it or anything. just not sure why this keeps happening.