I have always used seal bags for decals too as I think they kinda go 'off' after years of storage. I like the photo album idea purely for the ease of flicking through, but I wonder if there is a way of having them air sealed at the same time?
I found with some of my decals that are 10+ years old they just won't come off the backing sheet - even when left soaking for ages. Is this what happens to them when they get old - or is this just my bad luck?