J-MAN!!!!!
How ya doing? Nice to see you posting in the chameleon forum again!
Anyways, your set-up/husbandry/dusting schedule (etc etc) sounds more than fine to me. Considering this is an odd occurence with your female, it really doesn't cause me that much concern. Every now and again I find my guys on the floor of their cages looking black and distressed and I pick them up, inspect them for any traumas or whatever, find none, then put them back on a higher stick and they get happy again. I don't know why they go down there, but they do. Chameleons aren't the brightest bulbs in the box, if you know what I mean.
I don't think there is anything too wrong with your female, obviously watch for signs of trauma, bruising, swelling of limbs, bleeding, anorexia, lethargy, pale colours that kind of thing. If you see any of these signs, a vet trip is in order. If she is digging at the bottom of her enclosure, you've got yourself a gravid female and they can start producing eggs as early as 6 months of age, sometimes earlier. Maybe she climbs down there looking for food and can't figure out how to get back up? Maybe the cats are in her room and you don't realize it?
I don't know if any of my above musings has helped you at all, but hopefully some of it has. Keep us posted.
Cheers!
Trace