Graphic Glitch

make a 3 by 3 by 3 hole in a mountain and replace the walls with wood make sure there is stone behind the wall. if you take the new hay block and place it on the ground or against any of the walls when you break it the wood block behind/ above /below it will turn to stone for a sec before reverting back to the wood block. i belive this is a graphical glitch and not really a major issue