Looks like molting.
However, look her over very carefully for mites and lice, just to make sure.
Mites live on the perches, not the animal so you are looking for dark freckles on the skin where they have been biting, or eaten areas on the feathers.
Lice live on the bird and can be seen but are very small. They like hanging out by the vent and under the wings and leave crusty looking egg cases at the bases of feathers.