Cindy, can you post a photo of it. If it doesn't go all the way through, then I would not think it's a crack, but rather a casting flaw like Duke said. I've bought some that looked like a crack, but were actually a scratch on the cooking surface. A crack will go all the way through to the other side and will usually leak water, or show daylight when you hold them up in the sunlight.
Yair, don't get too excited about selling them for scrap. The last time I checked, scrap iron was bringing 5 cents per hundred pounds. Now copper and aluminum, that's a different story.