Other than removing whatever you have on the floor, there's not much more that you can do. Maybe, she just feels more comfortable being there with her baby.
How many other gliders are in the same cage? If there's more than just the daddy, she might feel that her joey is in danger if there's another female glider in the cage too. They do become overly protective.
You can read more on the normal weights on
[You must be registered and logged in to see this link.] Suz covers everything that you would need to know.