It looks like new feathers emerging from their sheaths in a natural abundance. Nothing to worry about. When I groom my roo I gently slide them off to help the feathers unfurl and to improve the showing appearance, but it's fine if you don't. They'll fall off naturally.
He is moulting and these are the new feathers (pin feathers) just starting to cast their protective sheaths. Moulting is an annual occurrence and generally happens in autumn/fall but can happen earlier or later with some birds. It is sometimes quite a discrete process where you hardly notice with some birds and others have massive bald patches that appear almost overnight with the coop looking like a pillow fight has been taking place and then turn into chicken porcupines when their pin feathers come through. There is usually an annual photo contest on BYC where people enter pictures of their worst moulting birds for us all to laugh at .... it also has an educational purpose so that people like you can see that even the worst case is still a totally normal process for the bird and nothing to be worried about. I will try to find the thread so that you can see that your guy's condition is trivial compared to some.