My Easter egger was doing it a week ago, so I am sure yours is fine, doing green poo can mean also that your chickens are under stress. Onetime I got my chickens from a breeder flock and there was a lot of stress for them because they were nervous scared and flighty because I would constantly hold them trying to tame them. They were also doing a lot of green poo. If your chickens are young like small pulleys maybe that is the age where they are nervous, active and very alert. That is possibly what it could be