Discoloured penis?

My male chinchilla is usually pretty good at cleaning himself, but I noticed by chance today that the base of the penis (when retracted) is slightly discoloured - it seems like a kind of greyish/blue/brown colour. I haven't been able to get him to sit still to have a proper look but does this sound like a hair ring?

If so I may have to take him to the vet since I'm having insane trouble getting him to sit still long enough for me to try and remove it :(