Over-achiever

I am hatching Ancona chicks as a favor to someone (this is not a breed I raise, I was given the eggs to hatch out). Chicks take 21 to hatch. Sometimes maybe 20, but 21 is "normal." I set eggs on August 1st. I heard some peeping today, but thought I was just hearing the cuckoo chicks that are out in the storage room. I don't have any chicks in the incubator room so I don't tend to look in there much. But I thought well I'd better check. Good golly there was a chick on the floor of incubator! Ummm...17 days. Okayyyy.. Anconas are apparently a little weird, so this gets added to the collection of weird Ancona stories. My first thought was that the egg must have been sat upon by a hen for a couple days before I got it, but that was not the case. They were collected fresh, and stored cool. When I candled them, at 6 days and then about a week later, I saw no differences in development. So basically this is really weird. It looks as healthy as can be! Sheesh.