Hair ring?

I just got my chin about 3 weeks ago. I noticed his penis sheath tip looks a dark brownish and i am unsure if this is just the color of his skin or if theres a hair ring thats cutting circulation off. I have tried holding him and unsheathing it but it won't go. Im scared because I've seen him down there unsure if he was licking or biting. :\ Im just worried because all the chinchilla penis sheaths I've seen before are always just pink.