Curious (at least for me) event last night, did ribs as usual (very cold ribs, raging river and mustard rub, indirect with plate setter feet up, and foil pizza tray under ribs placed on vertical rack, 240-250F), but last night they had a bark on them at 2 hours into cook. Only thing I changed was used two chunks (each) of oak and cherry rather than usual 2 or 3.
Sprayed with Shiner and apple cider vin. every 30 minutes to finish at about 4.5 hours, and they were incredible. Spritzing kept the bark from drying, so it was really tasty.
While the bark was tasty, not sure why it showed so early when I have never seen this before. Maybe the extra chunks of wood? If I would have done my usual "look first at three hours" I think they would have been messed up :( .