I have 4 red sex linked hens 2 production reds and 3 RIR hens. With a blue cooper Maran rooster. All about 6 months. I get about 4 to 5 eggs a day and the past 5 or 6 times I collected eggs noticed that one of the eggs was a different color it was almost white. And it is also a lot smaller than the others. Is this just because it could be one of the hens just started laying or is it the breed?
Each hen, even within the same breed, will produce her own shade of egg....."brown egg" layers can produce a wide array of shades of brown. As you are seeing a difference in color and size both I would say you are on the right track in crediting it to a new layer coming online.