Then they could have put old seed in the feed. Don't you think? I mean, the first conclusion people jump to, including me, is something is in the feed. I guess it doesn't always have to be that way.
I agree with this, I've had this issue as well. I know each of my hens' and roosters' patterns and habits, so I know when something's off. This happened to me aswell, except it happened in early spring when they were supposed to start laying after the winter. Not normal. I mixed my own layer...