its a perfectly normal action for an excited canine, its not personal, i try keeping a pup separated from adult dogs until they reach some sort of point of reason, because up till that stage they are attracted by more force than their body can handle, meaning they are attracted when excited to situations they are emotionally unable to handle, manage the pup as best you can without letting him get into too much trouble,
pups get themselves into situations and get spanked by a dog which may look harmless enough at the time but will only manifest itself when its temperament settles at 2/3 ye