I have a bunch of shipped duck eggs that are due to hatch in 3 days, well my last batch was due 7 days ago and I had several eggs pip the air-cell, but never pip the egg??? Why in the world would that happen, and does anyone know how long they can be in the air-cell without pipping the egg?! I have Cayugas that are pipping the air-cell, but it hasn't pipped the egg and it has been over 12-20hrs???