OH no! I bet you will still have a decent hatch, although a bit lower than optimal. 6 hours with a low of 70 or so won't be a death sentence although will slow them down. I've had eggs incubating for two days, then sit at room temperature (70 or so) for about 14 hours, then put back in and hatch. Hatch rate was only like 50% though instead of 90+.