Well, at the end of the day I checked in on her and she hadn't actually done any digging. I guess what I was hearing was her trying to get out. So, I took the whole laying bin and put it back in her enclosure, because I had to let the cats inside the house on account of it being so cold tonight. I figure now she's familiarized herself with the laying bin, and that it's not quite time for her to lay yet. I'll give her a bit more time. Also, today I observed what looked like the start of gravid coloration- black with yellow splotches.