Could there be a hidden nest somewhere? If they are out, maybe.
An egg eater, or nest robber getting into the coop?
Shortening daylight hours can affect laying, sometimes even this early in the season, or they are just pausing to make you crazy.
Did these 4 chickens just start laying recently? When a couple of my pullets started to lay, they laid for a week or so and then stopped. One stopped for a couple weeks before starting up again, the other was over a month. I heard it can be normal for new layers to do that.