I've seen just spawned trout have white to yellow meat, but that there I would assume is diet related, or possibly something genetic.

I wouldn't eat that one. Strange color!

Its hard to say really without knowing what lake. (I hope you don't take that ass being a smart a$$ as I respect your decision to not disclose your location) The reason I say this is some lakes are stocked with jumbo trout which are usually just trout that have been used for spawning their whole lives. Once the hatcheries don't need those fish they will stock them in lakes such as beaver lake that recieves jumbos every fall. These fish usually have yellow meat as they been pellet fed their entire life and have spawned once or more. Other then that it could just be eating snails can also contribute to them having yellow. I am no expert on this just speaking on I have noticed