Fall, hit top of head

SO loves to play with my 3 1/2 year old daughter by hanging her upside down or other stupid smurf. I always tell him not to because I know one time something will happen.

Well this time, it did. He was hanging her upside down, she was laughing and then she started to wiggle and fell right out of his arms, straight on her head. She cried immediately and then was OK after a minute.

I've dealt with many head bumps but this one was directly on the top of her head. I'm looking for the usual signs, eyes dilating, vomiting, etc. but is this like different because it was the top of her head? She probably fell about 5 inches down, maybe 10. It wasn't a high fall, just slipped out of his arms straight down.

Needless to say, he will NOT be playing like that again. He should have listened to me in the first place.