My boyfriend nutted on himself...

I’m currently a freshman in high school and this happened about an hour ago. Me and my boyfriend always go to this isolated spot under the stairs at our school during transitions. The only reason we go there is because we don’t like the attention people we know give us whenever we are up close to each other. The most we would do in public is cheek kiss and hugs. So anyway when we were at that isolated spot, we were making out, as usual. For the first time my boyfriend (I’ll called him B), anyway B started kissing me down my chest and ended up kissing my boobs but not nipple. I told him to stop so we’ll get to class on time and when we went to class... He told me that when he was kissing my boobs and chest he nutted in his pants.

Is this bad because we’re 15 or is it okay? (We turn 16 later this year)

(Edit: It wasn’t in the beginning of the school day. It happen before our last period.)