did you have a window in the room that let in a lot of sunlight? or did you keep high wattage lights on in your room a lot?
cuz i have had shoes out on a bookshelf in my room for years now, and i've noticed no fading or yellowing (i just have to dust them off here and there)... and i have DS pairs in their boxes to compare them too.
hell, even my white tokyo mids are the exact same vibrant white as the DS pair in the box in my closet, and they've been sitting out in my room since their release in like 2008...
but i have my window in my room completely blocked by 2 curtains, so no sunlight gets in, and i barely have lights on in my room.
i'm about to have custom shelves built tho, with uv resistant glass doors, to keep out dust mainly, but also light. considering picking up some of these containers for some of my other pairs that's aren't going in the display cases.