I roasted a duck some days ago, and while eating, the meat on the carcass slowly turned a sharp red, much like an apple turns brown. I can't find any information on this anywhere, as all questions equal "is duck meat red meat?", so my question is: what happened? I've never seen this before.
I have seen the same phenomena with cooked hamburgers and steaks. My research led me back to part of your question having to do with duck meat being characterized as red meat.
What differentiates red meat from white meat is the amount of myoglobin in the meat which absorbs oxygen from the air. All red meat, when exposed to air, will turn bright red. I have only observed this with raw or relatively rare cooked red meat so if your duck was not cooked beyond medium, that could be the answer. Like you, however, I did not find any material that cited the exact scenario you described.
Here are my links to the articles on myoglobin in red meat:
So there is likely a few different things going on here. One, the method of cooking is important in answering this question because when roasting, especially something like a full duck carcass the innermost areas are going to obviously take the longest to reach a desired temperature. We have to also remember that the density of the bones mean they are likely to withhold heat much longer than the meat that was cut from it. Knowing what we know about myoglobin, it is likely that after the meat was carved from the carcass the remaining meat was then being initially exposed to oxygen and due to the continued carry-over heat of the bones was increasing in temperature and continuing to manipulate the color of the meat. Also, the PH of the meat has a lot to do with the color of meat so the seasonings and acidity of your cooking may have something to do with it as well.