It is very normal. She's doing something that "feels good" and even though we(as parents) may not agree with what she is doing, she, as a child, doesn't see it as self-pleasing like we do, as adults. No need to freak out and think my goodness, she's already mastrubating, just re-direct her attention to something else that she enjoys doing. All children will eventually explore their private parts, it's just a matter of when. When she gets older and can understand what she is doing a bit better, just let her know that things like that are done in her own room. If you aren't comfortable with this approach, then I would suggest just always re-directing her attention to something else she enjoys doing. Honestly, the sooner you let her know that that belongs in the roon, the less you have to worry about it happening in public, because more than likely, it will. Just be careful not to make her feel bad for what she is doing, she doesn't understand (and won't for many years) that what she is doing is touching her private part. It would be like if you were to scratch your arm, b/c it feels good and someone tells you "that's bad." Good luck to you!