DD1 does it all the time, especially when sitting watching tv in the nud. I'm not too phased about it but the only time I do tell her to be careful is when she gets a toy or something that could hurt and touches herself. She has a little giggle so I know shes enjoying herself. I also distract her if shes doing it alot. I want her top be comfy with her body and not grow up with shame/guilt/embarresment like I did...and at 33years of age, I'm still getting over it!