My baby likes to play with hair. Both mine and hers. She pulls it, twirls it and enjoys running her fingers thru hair. Is this normal?

I have read that for some children, hair twirling is one of the self soothing behaviours. My nephew was the same and would tug at my hair (I have long hair) whenever I carry him. We taught him not to pull at our hair (his mummy, and basically any lady with long hair) as he doesn't seemed to know that it is hurting us. He soon learn that we are fine with him playing, but not tugging. He also likes playing with his hair and always seemed to be puzzled why his is so short as compared to ours.