I have a pot, I would call it the Dutch oven, probably about 5 or 6 quarts, and it has developed "blisters" in the bottom. The lining, on the interior of the pot, not the exterior, is wearing out and coming off in pieces about the size of a blister. Has anyone experienced this? This pot is old, at least 30 years old, but I thought the whole point of Le Creuset was that it was pretty indestructible. I thought that's why it is so expensive.