Well, after hoping it wouldn't, and being overly optimistic about it, Pandemic Pillow Play curled a LOT after the matt medium dried this past week! Such a bummer! Here it is taped flat on my work table so I can continue working on it by adding paint in the intersections of the photos.
It barely hit 20 degrees here in Massachusetts during the day today, and it'll be that cold at least through Sunday, so I've given myself the weekend off from walking, for safety's sake, and will be working on finishing up this painting this weekend, and hopefully doing what I need to to help make it more flat. It doesn't need to be perfectly flat, but it does need to be flat-ish.