I also have an Ameraucana, purchased from a reliable breeder, who lays an egg that is a little more green than blue. It does seem, however, that her eggs are getting a little less green over time. She's only been laying since January and is now just about a year old. Maybe yours will fade more to blue in time. It is still a very pretty egg. Like some of the others said, there may be a recessive brown gene and Mother Nature through you a little curve. Enjoy a prettily colored egg basket. Good luck.