After prior use, the pan might be insufficiently cleaned, causing the eggs to stick, resulting in an inadequate layer of food residue. Not all non-stick pans are equal. Some non-adhesive panels that are ceramic coated or copper do not work, and some teflon panels still require a little fat/oil to not be adhesive. Cooking and pre-heating food at the appropriate temperature is somewhat required in order to optimize the non-stretching property of the cupboard.