We have those Melissa & Doug Farm puzzle and planets puzzle. Admittedly, they're not in heavy rotation, but he plays with them now and then. We played with both of them last week, put them together on the dining room table, and then left them for a week. Today I went to put them away, and inside the boxes are these greyish greenish splotches. None are huge, but they're all over the entire inside of the box. I've seen that kind of thing before but never thought about it much, just figured it was old age in a box, never in MY boxes. Well, now it's in MY boxes, and I'm worried ... is this mold? The backs of the puzzle pieces look just fine, not a splotch on 'em. But I'm worried if it's mold then it had to have been there before we put the puzzles together last week and that maybe the entire puzzle is affected. Thoughts?