These 13 year old boys grabbed my butt during school trip? I'm 12?

So, I m 12, and recently our grade went on a school trip to this campsite, where we camped for a few days. At around 11 o clock every night the people there would put up a camp fire and make us do some weird exercises like squats. After that, we just wandered around and talked until midnight, our curfew. But anyway, during the time after the exercises these popular boys kept on running behind me while I was walking and grabbed, and squeezed my butt? Is this normal or is this sexual harrasment? Just wanted to know?