How do you know she's overdue? Is it now 23 days since you removed the buck? I only ask this because sometimes people say they're overdue but they're actually counting from when they put the buck in, not took him out (simple I know but worth asking). I'd guess she's hot, it is definitely warmer today and I was too hot last night myself. Maybe move her to a cooler area of the house if possible, if not put a fan on in the place her cage is kept. I'm sure she'll oblige with babies soon!