Totally anecdotal, so take it for what it's worth.
DS5.5, for nearly as long as I can remember, had a thing for starting a sentence, pausing, re-starting the sentence, and then repeating that process several times until he finally blurts out what he was trying to say. This is more pronounced when he's really excited about something. Doesn't happen all of the time.
This is not stuttering as far as I know. The psychologist that we had evaluate DS basically confirmed what I thought: his brain is working so fast that his mouth can't keep up. Sounds like something similar is happening with your DD.
Contrast that to one of DS's friends who is a little older (8). He has a traditional stutter where he's actually stuck on a single word or syllable.
I bet you the mechanics of what's going on in the brain versus speech center is completely different in those two cases.
What does your DD get stuck on? Single works/syllables or does she repeat sentence fragments?
JB