I just acquired a pair of Owl Finches (Male/Female) from a family member that recently passed away. I have owned budgies but never finches so I am doing some fast learning to get up to speed on these cute little fellows. I have had them for a couple weeks now and I notice that the female has some feather loss right around her black bar right under her beak area. I thought maybe she was molting but I am wondering if she has some other problem. Should I be concerned about this or just wait for awhile to see if the feathers grow back. She seems active and healthy and eats well. The male seems just fine at this time as well with no feather loss.
I have been giving them the same diet that my Cousin fed them. Along with the Owls I got all the supplies that she was giving them.
Here is what I have:
Full Spectrum Light
Heat Lamp
Finch Seed Mix
Dried Egg Food
Abba Mineral Supplement
Kelp Granules
Herb Salad
Crushed Egg Shell
I have also been giving them some broccoli and carrots since I give those to my Budgies. If there is more that I could give them please let me know as I want them to be healthy as possible.

Just to clarify...the feather loss seems to be just where the black bar would be on her neck area. Her face is not affected at this point.
If it was a mineral deficiency wouldn't it affect both Owls?