Many polymeric materials are tacky when swollen with solvent, but become brittle and lose tack when the solvent evaporates. The resin isnt being suspended, its being dissolved. There is a discrete but important difference. A suspension implies floating tiny (micron sized) particles, dissolving implies separation of individual molecules by solvent.
However, I agree that oxidation is more likely the problem. I was fishing for the time scale of the adhesive failing. Days--->solvent evaporation months--->oxidation.