A new and unwelcome type of adhesive

Update:

The Montenegro stamps have been lying on a side table for two months. During a frenetic, self-loathing-fueled, and, like, majorly rad stamp room cleanup a few days ago, I found them where I'd left them, and ... the raunchy adhesive may be going away on its own. Some of the stamps seemed dry and clean to the touch; others had remnants of adhesiveness, but it seemed insignificant compared to what they were like; one or two stuck to my thumb, but just barely, and for less than a second.

As I mentioned (or at least meant to) above, none of these stamps are particularly valuable or hard to get, but many of them look exceptionally bright and fresh, with rich colors and proud, sturdy paper. Only one is discolored, and that definitely appears to be from a typical hinge (or what appears to be a typical hinge). None of the stamps that had the rogue adhesive but didn't have a hinge show any stained or discolored spots.

I put them, and another dozen or so that I detached from the pages that day, on a couple of sheets of cardboard on a bookshelf. I'll check 'em out in a couple of weeks, and will report back.