You should get your child in to be evaluated by her pediatrician. There are a number of syndromes that could explain what you are perceiving, some of which are speech related, while others are general developmental issues. I'm not going to name any of them because I'm not a doctor and you shouldn't be getting your child evaluated by some random person in the internet. Wait until you have your diagnosis from a professional and then you can start googling.
If your child has any of them it is so very important to get early diagnosis and treatment. If she does not and this is simply normal development for her, you can at least gain peace of mind. Don't assume either way, but don't let your doctor dismiss your apprehensions if you feel strongly that there is a problem.
Don't be afraid to ask for a specialist's opinion. My daughter's GP dismissed our concerns about her speech delays for years. "Some children just start speaking later than others," he told us.
We finally took her in to a speech therapist who discovered that she has severe aphasia and apraxia. It is hard to strike a balance but I personally would feel better about erring on the side of being a touch paranoid.