L.N.
Hi B.~
Sounds like she just needs to be bare for a while. She is getting the idea, and better yet, it's all on her own! If you can trust that she won't go on the floor then just let her be. I don't think it will take long before she is really used to being clean and dry, then when you do put undies on her she'll be uncomfortable if she potties in them. I think she is right on track and this is just one of those quirks that some kids do...no harm done if it gets you to the ultimate goal. I know it's probably strange to have her running around naked, but perhaps a longer t-shirt or a nightgown for a while can help that (or maybe even a skirt...at home, of course) :)
Good luck...sounds like you are doing a good job at following her cues and letting her lead!
~L.