If it is really bothering you?, why don't you take her to a dr/counselor that is qualified to make this determination. We have one at our local childrens hospital which may be a good place to start. I have a neice that came to live with us when she was 4 yrs old. She was playing with stuffed animals alot & did sleep with them. She had a few large ones & one night i caught her on top of one riding it. It became a habit so after about 3 mo. I took her to the dr. Who worked with her once a wk & then told me to get her a baby doll & to keep it naked & have some playtime with her as much as she wanted to involving the doll. Playtime meant feeding,bathing, grooming, playing "teatime" etc. I did and after another 2 mo between me & the dr, we determined she had been molested. By her stepdad who had only been in her life briefly for 6 mo between the sge 3-3 1/2 yrs.. The doll thing worked for us. It may be an idea and the dr. too. Better to be safe (no doubts) than sorry.
I tend to agree that a child doing something because it is tactile or sensual usually doesn't have much to do with sexuality as an adult would define it. There are more nerves in that part of the body than some other places, maybe she just likes the feeling of her fuzzy stuffed animal against her bottom. (I don't think an abused child would be putting a stuffed animal into her underwear and acting happy about it. Abused kids don't think sex is fun.) I think she was just being a kid.
As to my latter comments, what I mean is that describing the physical explorations on the part of the very young as sexual may be the superimposing of our adult perceptions, and not sexual at all, unless you want to classify all sensation as sexual. But even Freud said, "Sometimes a cigar is just a cigar."
I offer what I say only as a possibility. I do not know either the parents or the child. However, I have witnessed excessive stress on the subject. Yes, little girls can be very touchy-feely. I don't know that it is specifically sexual just because sexual parts may be involved. Little children may lick the skin on their arms because it is so smooth and silky. I have seen two little girls lick each others tongues and giggle because it felt funny. I didn't see that as sexual.
allmymarbles, please. A trusted and caring person asking a small child if she has been touched inappropriately does not create a child's interest in sexual things. People are pretty tactile creatures even when little. As RockRose says, some kids find their privates surprisingly early. I had a niece who would rub her diapered vulva area on the couch arm (much to her mother's chagrin). Little kids also sometimes hold onto that area for reassurance or comfort.
Megan, I would be worried if she had personality changes, such as withdrawing or acting out in an angry way, or acting out with other children. It sounds like what she is doing is mild and invented by herself, if for a little sensual pleasure or for psychological comfort. It doesn't sound like someone is doing something to her.
Is it possible you over-talked the sexual question? If so, you may have unwittingly aroused an interest that is somewhat premature. Children are curious creatures.
Megan, I think some girls are just very sensual from babyhood.
I think if you look back through this forum you will be amazed at how many baby girls masturbate.
It's just a matter of finding out what feels good and is comforting. I don't think it's about abuse.
Best wishes.