If you washed your cast iron skillet in the dishwasher you should be able to re-season it. Here's a link to a blog about caring for cast iron cookware:
http://www.missionrs.com/blog/?p=20
no, warm water and gentle soap
Yes, cast iron enamel cookware is dishwasher safe! Cast Iron is extremely tough andd very durable!
Dishes and pots lined with enamel are not porous on the cooking surface and therefore do not need the oil seasoning that cast iron does.
Many of the newer enamel coated cast iron cookware manufacturers advertise their products as safe for use in the freezer, as well as the dishwasher. Traditionally, the answer would be no. In fact, many would cringe at the thought. My grandmother would tell you to keep your cast iron out of the freezer and the dishwasher or you'll ruin the integrity of your season coat (and I would agree.) However, the most unbiased answer is that you should check with the manufacturer of your cookware.
In 1883 he enamelled a cast iron horse trough, so yes, he invented the enamel bathtub.
The biggest advantage to an enameled cast iron pan is you don't have to prime the pan, You can also wash the enamel pan after each use, unlike non-enameled iron pans. The biggest con to using enameled cast iron pans is that the enamel contains heavy metals and can be bad for your health if pieces start to break off.
According to the article on Fine Cooking, enamel cast iron should be allowed to cool before washing to avoid cracking. Soaking for fifteen to twenty minutes can help loosen food residue. Finally, avoid using steel wool, which can damage the enamel.
Cast iron enamel cookware can handle very high temperatures but the enamel layer can be delicate and susceptible to scratching. So, after washing, make sure you gently hand dry with a soft towel and avoid scratching it on the prongs of the dish washer. Also, when cooking in the enamel cookware, use a wooden or plastic spatula instead of a metal spoon to avoid scratching or damaging the enamel layer.
If it's a name brand, send it back to the manufacturer. If not... if it's just a chip in the enamel, you might be able to use the Aga enamel repair kit (I have not tried this). If it's a hole through the cast iron, I don't know of a way to repair it, although a blacksmith might be able to do it!
Paint or enamel can protect iron from rusting.