Heavy breathing can stem from a lot of things from bacterial, viral or respiratory ailments, egg binding, liver disease or any other organ disease that cause the breathing cavity to take up the breathing space.
Noisy breathing can stem from similar issues along with deflated air sacs and heart valve problems. If the bird has ever worn pinless peepers, sometimes these can destroy the nasal cavity and make it difficult to breath or they can whistle when they do breathe.
Sometimes molting birds do breath in a lot of that feather skin and can have breathing issues, although it shouldn't be all that noticeable.
If this bird is eating, drinking, pooping and is active enough considering she is molting, then there isn't much to go on as far as what might be causing her noisy breathing. There would be other symptoms of the things I have listed.
So I would say just watch her carefully for a while. This just might be the way she has always been. But if she starts in with anything respiratory like runny nose or eyes, coughing or wheezing, you might get her started on some antibiotics. Watch for coccidosis as well...stops eating and drinking, sometimes blood in the poop, fluffs up, sleeps a lot and off by herself. Birds moved to new grounds can contract cocci quite easily.
I sure hope she is ok!