Just want to pass along something... I had got several Commemerative Panels in a trade awhile back. I dont collect that format, but figured I could use the MNH stamps from them for my collection or to use as trade stock. Well, it seems that when they put the mount onto the panel card, they use more water than needed and some water gets into the gap on the back of the mount and in contact with the gum. I had several of these that now have disturbed gum from being in the mount when the mount was mounted to the panel. So don't assume the stamps you have in these kind of Commem Panels are MNH, they could have disturbed gum! Here's an example of what one of the panels looks like before the stamp is removed.
Not unusual for a post office promotion to be faulty. Most of these were for impulse buyers /hopeful investors. Canada post also had numerous items that ruined the gum, some intentional to adhere them to printed product.I laugh when I see people trying to get top dollar for those gold foil stamps that were promoted as investments.