3 year old son hit my newborns head on accident. Is she ok?

I layed my 4 day old baby on my bed so i could change her diaper, my 3 year old son was asleep and i guess moved and kicked her head. She started crying but as soon as i picked her up she seemed ok. Not sure how hard he kicked her but i believe he did hit her head. Should i take her to er? Shes awake and has the hiccups and is laying on my chest now.