Ay, alam ko yan! A few of us moms noticed the same thing with our babies around that age, head banging, pulling hair, sometimes even biting themselves when they get frustrated or excited. Kadalasan normal lang yan, lalo na if he's testing boundaries or frustrated na hindi pa siya magsasalita ng malinaw, pero since palaging niya ginagawa or medyo malakas ang impact, mas better kung check mo with your pedia just to be sure walang underlying reason or kung paano best ma-redirect niya yan.