Three day old pancake batter with grey spots
Yes, the pancake batter is going bad and bacteria is developing. No mold is good. In a restaurant environment I would sometimes keep it over night in the fridge but not any longer. From a food safety standpoint, food should not be left out longer than 4 hours before being discarded. Just because it does not smell does not mean it is OK. Pancake batter is cheap so tossing it is no loss. If you are asking your question from a chemical reaction standpoint, I am sorry I can't help. But I do not think you would want to go to a restaurant and be served pancakes with grey spots.