If you have only recently acquired them, then maybe the move disrupted them a bit. We had a hawk attack several weeks ago, and one of our girls was taken. Over the next several days, we had all kinds of strange eggs. I think they are creatures of habit, so if they are disturbed in some way it shows in their eggs. If you have some extra shells, you can sterilize them in the microwave and grind them up and feed them back to your chickens. Mine don't like the oyster shell, but they seem to nibble on the sprinkles of egg shells. Plus, I like knowing the entire egg is being used.