It appears the knife was exposed to water/moisture and the spacer material swelled up.The result was that the handle scale lifted up on the rivets. Best choice is to remove the scales,flatten them as needed,and replace the spacer material. When reattaching the scales I would recommend replacing the rivets with Corby rivets. That should prevent this from ever happening again. If you are not set up to do this, I would be glad to do it for you.Send me an email.
As a side note, this is a classic picture of what happens when the scales are clamped on so tight all the resin is squeezed out of the joint.Having lots of holes in the spacer material,and extra holes in the tang will greatly prevent this from happening to your knife.The tendency to want the rivet hole a "press tight" fit, and to clamp with high pressure excludes all glue from the handle.What little there is left won't hold up to much pressure. I have repaired handles (some of them mine) that showed no sign of epoxy at all between the scale and tang.The clamp should be only strong enough to hold the scales firmly in place while the glue is drying.The rivets should slide smoothly in and out of their holes,and the rivet surfaces should be scored by chucking in a drill (do the whole rod when you get it) and rotating against coarse grit sandpaper.