Mcubed, I AM SO HAPPY!!! I was exactly the same way as you, and I thought about that after I yelled at you ;-} to get down on the floor and look up. It took me forever to do that, it was like I didn't want to believe that there were more light leaks cuz in my case, I doled out a lot of $ for the grow box and I wanted it to be perfect. I finally reached my wit's end: my temps were good, my preventatives were there, but wtf??? I had to do the same kind of tweaking you're doing right now, to get rid of light leaks. Then the problem stopped. I think I'm gonna suggest to Nebula that she put a little more emphasis on the light leak issue in DWC tubs, boxes, closets, etc etc etc.
This is so awesome, you've solved this problem and you won't have to deal with it again because now you KNOW. This is how we help each other on this forum: I know you'll pay this forward with others cuz you'll KNOW!!! ;-}