Hmmmmm, I have a 3 week old ameraucana that has three rows. And thanks for the advice =) I'm using a local brand of feed. Thanks for answering all my questions! I've had chickens for quite a while, but I'm realizing that I still have lots to learn, as well as new breeds to have! I love black and splash ameraucanas. I'm hoping one of mine is a splash, but at the moment all the feathers are coming in with a silvery color, I'm not sure what it will be! Were these eggs shipped? Or did you drive to get them? I've heard a lot of bad things about getting shipped eggs.
I wouldn't worry too much about the 3 rows, I've had some very definite pullets have 3 row peas from early ages. Of course, this was in Easter Eggers, not Ameraucanas, so there may be a difference there. So far my Ameraucana pullets have all had small, thin peas and the boys had thick, three row peas.
This is one of my pullets with a 3 row comb at about 6 weeks: