Cecal droppings happen about every 10 droppings and are perfectly normal. If it's just occasional, then that may be all it is. Particularly if every one is acting normally, eating, drinking, etc.
https://the-chicken-chick.com/whats-scoop-on-chicken-poop-digestive/
https://the-chicken-chick.com/whats-scoop-on-chicken-poop-digestive/