I agree. I have a clutch of 18 corn eggs this year. The first one pipped on June 26th (day 60); it's now July 3rd and all but one have hatched - the last one pipped this morning. That's 8 days from beginning to end of hatching, and since most of mine have pipped for 24-48 hours before hatching, it could be 9 or even 10 days from start to finish of the hatching process. I think I have a temperature difference across my incubator as the same thing happened last year. I would leave well alone for a few more days. Although the books say all the eggs should hatch at roughly the same time, I must say in my very limited experience of two corn clutches, this has not been the case. Just to add, all my hatchlings seem healthy and were last year too - just waiting for number 18!