Hi, I'd like to help you with your question.
It sounds like from what you describe that your daughter may be acting age appropriate. At your daughter's age, children start to become more sexually aware. That is not to say they can handle the topic as would a teenager, but they do start to become more curious and are ready to ask questions or be told about pregnancy, birth and the role of the opposite sex.
Children of your daughter's age also becomes more aware of society's role in sexuality such as displays on television, bad words on the radio and off color jokes by comedians. Although they cannot completely understand what they hear, they begin to see the difference and understand sexuality.
It may just be a matter of sitting down with your daughter and letting her know, in a gentle manner, that her actions are not appropriate. She needs guidelines for her new found information and what is appropriate behavior and what is not. Let her ask any questions she wishes and answer in general, yet informative ways. She needs honesty but not excessive details at this point.
Also be aware of any other behavior like what you described. Any type of continued behavior on her part that appears too adult like or feels too inappropriate may require a closer look. Be sure she is not being exposed to anyone who can harm her emotionally or physically, just as a precaution. We always need to be aware of the people around our children.
I hope this has helped you,