DURR, did you have any low temp issues? I did, and I figure that's why mine have started hatching a day late. I have one pipped and my other 2 eggs have just started to peep. Then I have 3 more that are a day behind (never going to stagger hatches again, its just a pain). I had 2 really cold nights where I let the house get too cool and it delayed them until today. If your temp was off for longer, that's probably why they're late.
I don't think I'm going to do anymore hatching in my incubator until the weather is a little more consistent. Its just too much of a hassle with my cheapo bator. I've got a hen sitting on eggs now, and these babies hatching at some point over the next few days then I'm done until it warms up...unless I get more broodies. They definitely do a better job than me :/
Nikki