Inappropriate behaviour??

[lvandljmum]

my 7yo DD has always enjoyed playing with herself. Even when very young she used to wriggle around in her 5-point harness, and along with appropriate noises, skooch about until she was, well, finished..She has carried on with this behaviour, mainly as a comfort thing when shes tired,stressed, worried etc. To be honest Ive been ignoring it in the hope thet it will stop on its own. But now its been mentioned by a friend following a sleep over. Friend not at all concerned, recognised it as a sign of dd not being comfortable in situation and reacted as I would have (she truely is a good friend).But now i`m wondering if I do need to address it or can I continue with my ostrich approach??
Help

Its perfectly natural, just explain she can do it in private, my ds is 7 and has been humping teddies/cushions for as long as I can remember

I keep telling ds (same age) that he is not allowed to do it in public, that it is basically not polite. Like showing your bottom, once your above a certain age, or picking your nose or chewing with your mouth open. Not shameful, just something other people don't wish to see.