3 year old won't stop touching herself

My 3 year old is potty trained and wears big girl underwear instead of diapers. She's recently learned that she can touch herself down there. I tell her that's something to do in private when nobody is around! Todayshe wore a dress with no shorts on just underwear and we were looking for a new puppy and she was sitting on the ground with a dog she had her legs open and touching herself in freaking public. 😣 how do I get her to stop! I know it's normal for her to explore her body. Has anyone had this problem?