I've noticed that my brindle and my black white and tan basenji both developed thick undercoats in winter but my two red and white B's did not, though I'm not sure why that was.

My 3 year old B had that issue when she was younger. Our vet said that smaller dogs can't always pop their own anal glands, and that she may need it done for her about once a month. It was difficult even for the vet to express them. After awhile, as she got bigger, it stopped being a problem. I hope your B's problem will improve as he gets bigger, but definitely have him checked out by your veterinarian.