I know people are positive that diet has something to do with this. But truthfully, I am not sure that it does. Maybe a long term effect, but often times chickens really don't live that long. In my experience, it happens, then happens again, and I begin to think I need to do something about it...
Yes, this happens. It is really not a big deal. Most of the time, (as in all of mine over years) they lay perfectly normal, and then you will get a glitch, and sometimes you will get a couple of glitches, and just when you are sure the sky is falling, they start making perfectly normal eggs...