daycare moms

So my daughter (8months old) started daycare for a few hours a week about a month ago and today was her first full day at daycare and she hit another baby who is a few months older then her, not just once but three times today and the last time the other baby hit her back. Is this a normal reaction to daycare only children have? Should I be worried that this might continue? Is there a way I can stop this behavior fast?