Orgasm from nipple stimulation?

The other night I was at my boyfriends place and at first we were just cuddling but eventually it lead to more. But I was giving him a blow job and he started playing with my boobs. The more he did the more turned on I was but as he was getting close to finishing it felt like I was about to orgasm too even though he didn’t even touch me down there. Has this happened to anyone else? I’ve never had this happen to me before and I’m just curious.