I have an odd question for all of you cast iron cooks. I made apple crisp in my dutch oven and cooked it in the coals today at ZealYouthGuy's Buckeye Campout. Well...every part of it that touched the cast iron turned blue-ish purple. It looked like blackberry apple crisp. It seemed to taste fine, but the color change was so odd! Could something that I had cooked in there previously have affected the apples? I'm baffled.