Bag-cooked omelettes turning gray when stored in the fridge So, we found the omelette in a bag recipe, and decided to use it. Pretty simple, beat the eggs, drop in ingredients, (Usually either Great Value Mozzarella, Fiesta Blend Cheese, or Cheddar) and some Jimmy Dean's Breakfast sausage, boil for 20mins, done. 

We store them in the fridge since we don't have time in the mornings, and eat them throughout the week. They're perfect for my father who eats them at work (microwaves them, about a minute or so) and for me if I'm looking for quick meal.

Problem is, that at times they turn a grayish color, as they're put onto the plate and break up the omelette, you can see grayish/black spots. 

Are we storing them wrong? Are they safe to eat? Any suggestions would be helpful.
Cooking, not storage, to blame
Storing cooked eggs under refrigeration for a week is not turning your eggs gray. Instead the discoloration is from the iron in the yolk reacting with the sulfur in the albumen at temperatures of 170F or higher creating ferrous sulfide.
Overcooking the omelettes initially, or perhaps hot spots from the reheating method, create the gray-green discoloration. While unappetizing, the discoloration is not harmful.