Does anyone know why some of the Wii U games come in red cases instead of blue?

I can't find much information online. I found a thread at Game FAQS discussing Mario Kart 8 and it seems to have been the first title to come in red. There are several other games like Super Mario 3D World and Mario Party 10 that I have seen come in both blue and red cases. It seems to be only first party titles that have this variant. All third party games are strictly blue from what I have seen.

Are the red cases maybe first production run and blue cases are subsequent production runs? I would assume there is something to it, or maybe Nintendo just got a surplus of red cases and are packaging games in them at random?