Normal
She seems to be ready to molt (she looks quite dark). I do not see an issue with the enclosure. Just make sure she has fresh water and that it is warm enough where you have her. Check also for any draft or anything that could blow by the enclosure. Last but not least, maybe she is just displeased that the beta is getting a 15 gallons tank when she is in a plastic critter cage (she's obviously not aware that you have something better on the way).