Does my 9 year old step-daughter have social/maturity issues?

My step-daughter, Becky, is 9 and only talks about boy (friends) she has at school.  She has a self-proclaimed "best-girlfriend" but when we try to set up times for them to interact outside of school, the other girl's parents seem to blow-us off and even commented (in a round about way) that her daughter is of a higher maturity level. Now normally I would have taken great defense to that comment, but I have doubts myself. Becky is constantly in people's faces. Not just with friendly salutations but literally IN THEIR FACES. My 13 year old nephew put it a really good way "Becky - you are always in people's bubbles!" he said.  She gets to the point of sheer annoyance and makes people not want to be around her.  We obviously try and discourage this behavior at every opportunity, but it only seems to be getting worse.  Her mother thinks she is just outgoing, but when a 9 year old girl walks up to a group of 40 year old men she's never met and starts a conversation and hanging on them, that is NOT JUST outgoing - it can be downright scarey sometimes!  She is always hanging on anyone in her general vicinity and sometimes she gets a little too friendly in areas she shouldn't.  (She has touched my chest on several occasions and acts like it's an accident each and every time).  I could go on and on, but I think you get my point.  I am sincerely concerned about Becky, especially since Becky's father tried talking with Becky's mother about it and got nothing but denial and basic refusal to check into the matter further.  Any guidance would be greatly appreciated as we are at a total loss.