Aggression or playing?

This is my puppy baby z. Sometimes she does behavior like this and I don't know what to make of it. Is she trying to play but just doesn't know she's coming on too strong ? Or is this aggression? I can't tell. I lean towards it being play because almost every time she exhibits this behavior is like when we're outside usually playing fetch. She'll fetch the ball a few times then all of a sudden she'll come running toward me barking and do this behavior. Does anyone have experience with something similar? She's around 4 months and I really don't want her to continue with this behavior as she gets bigger