mold happens on occassion, and it is not neccessarily going to have any negative impact. minor mold blotches on healthy looking eggs is not a problem, and I would be very weary of applying antifungals. When I asked similar questions of my veternarian, he described to me eggs that had turned five different colors with mold, and hatched out fine. He also pointed out that application of antifungals can kill as many eggs as it might aid.