im not totally sure if you can say calcium deficiency is the cause of floppy tail. they try to cover that in the rhacodactylus book, but i think they say the exact cause is still unclear. i have a female that has floppy tail, and she has always had plenty of dusted crickets at her disposal. it's just one of those things that seems to affect some cresteds, while most dont experience it. anyhow, ive had cresteds that start spending more time around the bottom when stressed out, particularly last summer when i lived in a house for a month and a half with some girls who had a few cats. i did my best to keep the cats from pestering my gecko, but every night they would jump on top of the cage and stare at the poor lil guy, no matter how much i sprayed them to keep them away. he had always slept up in the branches during the day prior to that, but he began burying himself when i moved there. it's almost been a year now since all of that and he's doing just fine. give her some time and im sure she'll be back to her normal self.
good luck