I think that, because of the late set position of her, she did some late resistance on the blocks wich did the false starting system to go off. It’s like Jon Drummonds false start, he didnt move, just added too much pressure on his blocks. Anyway, her fault, set is set and you don’t have any reason to wait for something.
It wasnt about she going up fast or slow, she intentionaly moved to set much later, she did it already when she did the first false start. It looked strange because of the other girl going off to fast. It would be alot more stranger when the other girl would not have done that. Then it would really look like Drummonds false start.