I moved to the Philippines to retire 4 years ago, and now both my accustics have suffered the same problem. Both are high end guitars. In both cases the bridges has lifted. The first guitar happened a couple of years ago, and I just noticed the other one has the same problem. I was able to remove the bridge from the first one, but it took me awhile to get the right C clamps for gluing.

First, any idea why this happens, and second. what kind of glue should I use?

Thanks