Actually there are three components to bird waste. There's the most solid part which is feces, the whitish creamy-colored pasty part which are the urates, and a bit of clear or yellowish fluid which is urine. In fact, all birds HAVE to have urine because it serves the crucial role of flushing the urates out of the kidneys and into the cloaca. To some extent, the three components are mixed before exiting the cloaca, but if your chicken were to 'go' on a white piece of paper, you'd normally be able to distinguish all three components. It's easy not to notice the urine in a coop or on the ground.
A change of color from white in urates to orange can indicate a health issue (such as coccidiosis, giardia, Marek's or other types of avian herpes, etc.), or it may be as simple as the bird eating a lot of red and orange matter. I'd be inclined to keep a close watch, if possible, quarantine your white, and see if it continues. If it repeats much, it'd be best to have the poo analyzed by a vet. If it isn't possible to do that, I'd go to the feed store and have them recommend a soluble broad spectrum antibiotic to go in the waterer. If you do that, follow the directions carefully, and don't eat eggs from treated hens until after the recommended waiting period.
Mark