Sometimes, depending on how the eggs were stored, or if they were in a nest being warmed by the sun etc the eggs can start to develop a little bit before being set, or they could have been in warmer areas of the incubator that made them develop faster... so they will be the ones that hatch first. Completely normal, and I have been caught off guard many times, lol so I know how you feel (I hate rushing or being rushed!). It's rare that all of my keets hatch the same day tho. Good luck with pulling out the dry keets. Post some pics if you can once you get them in the brooder.