Older rats being a bit overbaring to new babies

My little babies have ended their quarantine and are being introduced to the older boys using the carrier method. They generally get on but the second playdate the older boys kept pinning down the little ones and like aggressively grooming them, and sometimes I wasn’t sure if it was fighting. The little ones definitely didn’t enjoy it. They weren’t hurt but it makes me anxious. Is this normal or a sign they’re incompatible?