Toddler masturbatory behaviors

My daughter turned 2 a few weeks ago. She's still in diapers and we're slowly working on potty training. Up until recently, haven't had any sign of the toddler masturbatory behaviors. Recently, when we finish up bath time and I am wiping her off with the towel, she will sometimes grab a corner of the towel and kind if rub it on her labia. She only does this for a few seconds and usually stops when I ask her to. Beyond that no issues with diaper changes or any kind of self touching.

How did you handle those kinds of behaviors with your kiddos? I don't want to shame her, especially when she grows up into a woman, and I don't want masturbation to be something taboo for her, but at this age, is it ok to say something like "that's not appropriate, honey?" She responds really well to the idea of "inappropriate behavior". (I.e. I tell her picking her nose is inappropriate, or hitting is inappropriate, and she stops immediately).

Secondly, after your kiddos were potty trained, did you she any issues with increase in these behaviors? Maybe when self wiping? Or with more access since they are in underwear instead of a thick diaper?

As a psychologist, I know these behaviors are a normal part of development but I don't specialize in early childhood so not sure how best to approach them. TIA for any useful tips you might have.