Linda
The only thing I know to tell you is to go with your gut on this one. I'm speaking from both angles, the abuse hx and her age.
I know that girls younger and younger are behaving outragiously and inappropriately provacative. (personally makes me sick to my stomach) It still doesn't make the behavior right or appropriate. Behaving in such a manner can get a female into deep trouble with the opposite sex. Something no one wants for their daughters.
Now that kt is entering the teen years she's going to need tons of guidance from you, and husband as well as to what behaviors are acceptable regardless of what the other kids are doing.
Sex is an open topic in our home and can be discussed at length at any given moment. But inappropriate behavior my one of my kids got them called to the carpet immediately, and then an explaination as to why it was wrong to act that way, things it could possibly lead to ect.
It could be her hx rearing it's head with the hormones, or it could be she's just copying behavior she's seen to see if you'll let her get away with it. My point is, if you feel the behavior is inappropriate, then it is. Simple. The not so simple part is explaining it to her. lol *sigh*
This is why I think girls are sooooo much harder to raise than boys, especially once the teen years hit.
hugs