The oven is only 2 months old, I recently bought an induction pan and with prolonged baking a circle appears on it, as if discoloration on the plate. It doesn't go away and it is kind of rough slightly from the rest. The frying pan has a hole in the center and I think this is a problem, but I do not know it. I am asking for some advice, can it be removed by some means or just to give the pan a guarantee?