Did you just leave the area and end up with the jar in your inventory? I wouldn't say it's a particularly valuable find, but if you didn't do anything and this is actually a vanilla kind of glitch, you can always report it to jagex...
Does yours have moths in it? With moths in it its not tradeable. It is bankable but does not note. When u go back to mini game it takes jar back in exchange for exp even if it is still in bank. Cannot be fed to troll. Hope this helps.