it is likely an area that isn't fully calcified. If you have candled it and it shows veins then leave it in with the others and it will probably be just fine. I hatched one with a large "window" as they are called. You get a look into what is happening in the egg as it develops. It is very cool! Do a quick search on the forum here for "window egg", the picture of mine may show up.Congrats on your clutch!
http://www.ball-pythons.net/forums/s...ght=window+egg