No_Biz is certainly a poster and a mother on Curezone whom I have admired a great deal, and I think it's specious to say that she, after her initial post, is "unconcerned" in any way -- relatively or not.
My daughters spank the monkey, and they have never been to school or otherwise had an opportunity to be molested. When I talked to friends about this, they all had a story or two to tell about themselves and their daughters. (My favorite was my friend Jayne's, whose boss's daughter liked to rub against the couch in the living room; when guests came over and she began doing it, her mother suggested that self-gratification was something the girl should reserve for private places, and her daughter, in front of all the guests, asked if she could take the couch into her room!)
My daughters' self-gratification really began at a similar point -- when we moved them into their own cribs for naps -- and I wonder if it isn't part of self-soothing post-detachment, as someone suggested. (It seemed to be a phase for them, as so many things are at this age.) self-gratification, from what I've read, is not only sexually satisfying, but is a great stress-reliever as well.
I'm sure No-Biz will use her judgement around this issue. I'm not sure she came here and posted her question to get accused of poor mothering and/or child abuse. This post really crossed a line.