No it doesn't, and it's different for everyone.
Sorry I should have elaborated. I see that this is a 7 year old girl, but you don't say how much she does it, or much about her which would help us answer your question. Is she doing it a lot, or in public? How is she otherwise? It's normal for kids to do this, but they need to be taught that only in their room in private.
And what about elder childerns 10~13?Is it not good for my 13 yo son?
I think what children look for is to understand, they don't know many things and they explore them all, so if you could have a good child sex ed book with graphics so they know the physiology of it and that it's something you could do once a week or so, because as anything in life is about administrating and balance, if you win something, you lose something else, you gain pelasure, you lose sexual energy that helps you do other things in life.
Also there is no obligation to do it nor not to do it; so i think this way they learn to be responsible and measure if they should have sex, masturbation in this case, and this works for the rest of their lives. The thing is, parents treat them like idiots, keep them in the dark and don't teach them anything about it, like it was OK to be ignorant and draw their conclusion from ignorance and selfish convenience, because parents construct a emotional fictional bubble around them, so they learn about sex and other things that way, so giving them the info they need to responsible about their sexuality and their life is always important, treat them as responsible smart beings.
Also I think is very important to teach them that it should be an act or love, caring and intimacy sometimes, not such pleasure, and that can be done with a partner when they feel like it's natural later on in their teens, and then teach them to use protection, and be treated with love.
Also, have been discovered that sex and orgasms generate in the brain conditions and biochemical substances very much like being 'In Love', so might generate crushes on their classmates, and rejection from them, this could lead to loneliness, feeling rejected, introverted, even Depression, feeling sad all the time.
I think this should be taught to children, how to administrate their lives, consequences and trade offs, so they live them well, be good citizens and help others in need, whose parents didn't teach them this.
The future generations behavior depends how we inform them and guide them, so saying do it in your room, is just bad parenting, mediocre at best; we can do better, then we should do better.