The Cover Boards are a natural product made from high quality Maple or Walnut wood by experienced professional woodworkers. It's possible that after the Cover Board is made wet or a new board is exposed to a dramatic change in humidity that the board can start to feel rough or "fuzzy". Wood is made up of many tiny fibers. Even after being mechanically sanded with a high grit sandpaper, there can still be small fibers on the surface of the wood - almost like hair follicles on your skin. The wood will feel perfectly smooth when dry, but when the Cover Board gets wet it can make the wood swell and cause these tiny fibers to stand up making the wood feel rough or "fuzzy". This is a normal phenomenal and while it doesn't happen to every board it does occur more often in Walnut than Maple.
The good news is it's very easy to get your board back to buttery smooth with minimal effort and 2 minutes of work. You can simply lightly sand the board with a 220 grit or finer sandpaper and reapply a coat of Steelmade Wood Oil, food grade mineral oil, or another oil of your choice according to the Cover Board Care Instructions. It's possible that you may need to repeat this process if the board becomes wet again.