All of my birds are hatchery quality, including my EEs. With few exceptions, all have color changes to their eggs. At the beginning of a cycle, my brown egg layers lay dark brown eggs. As the cycle continues, they lighten before starting all over as dark again. Same goes for my EEs.
I mention that they are HQ, because I believe (but don't know for sure) that has something to do with it.
Interesting. Our barred rock lays brown, always. I have noticed that the blue greens ones change shades, so that's probably it. Our girls aren't quite a year old yet and have just started laying everyday, so shade variation makes sense. Thanks ladies.
One of our EEs started laying a very light green egg. Lately, her eggs have been so pale we have to hold them next to a white egg to see that there is any color. It is probably just a pale variation of her original color.