I would bake that box for a while, if you spray painted wood, it's going to outgas for weeks as the solvents in the paint soaked into the wood. I'd say leave it out in the sun for a week, but it's the wrong time of the year in Oregon. I guess a small fan heater will help.

Black with redish tint and edges sure sounds like a light leak, it really doesn't take much light either if it sat for a week in a room. 2 min in a beseler drum with the light reflecting thru the fill spout from the a 2x40 watt fixture on the ceiling leaves a nice red spot.

BTW black foam neoprene weather stripping helps keep the light out, it works very well on the black plastic commercial paper safes.