Brown stain on Budgie's feathers

by Grace
(Charleston, SC)

My Budgie has a brown stain on the feathers above her nostrils. It was barely noticeable when we got her about 2 months ago, but is gradually getting bigger. Is this something to be concerned about? She is shy and mouth breathes when people come around and her breathing rate increases. I don't know if she mouth breathes other times.