Ferret kit being thrown out of nest ?

Keep an eye on her and see if its the same kit, if it is she may scenes that its a weak one and doesn't want to waste her energy on raising it. If not they can wiggle out of the nest (make a better nest where they can stay secure). The mother may be trying to move them to a (for what she thinks is) a safer place; just watch her and see what she's doing.