I seem to be experiencing a problem with the server plugin that reveals ore when a player sees it. I've noticed a couple of times where I would mine out a section of wall and a part of the wall that was already visible to me would suddenly spawn some ore. It's not that a torch wasn't already there or that I wasn't able to see that particular block in the first place, it's that I would take out a block on a wall of my mine and suddenly some formerly blank stone blocks would become coal or any other ore.