Why do some hatch early?

[Promiselandfarm]

Last night I kept hearing a noise that sounded like a little chick. I asked my husband if our son had taken some chicks into his room. He said not but I kept hearing that sound. I thought I know I hear a chick. The incubator is in my son's guarded care, it is his domain. This morning he brings me two banty chicks that were all dry and were not even due to hatch for days. They had not even been moved down yet and were still being turned. Why do some chicks come early? Temps are good everything is good. It is really not a problem just wondering why??

 

[shortcake1806]

Usually the incubator temps were high when they hatch early. Just wondering if maybe since it's warm outside they started to develop before you put them in the bator. That maybe completely crazy though. I'm sure someone more experienced than I would know.

 

[Promiselandfarm]

Temps here were warm around the time we started them but now they are not. So I have no idea but that may be a thought.