I dont think it has anything to do with it that coz you remember the story you have a grudge. But think about it if you are in a really bad mood and everything is going wrong – if you’d think about that story would it make your mood worse or you’d stay the same as you were before…
in other words do YOU think you have a grudge? Maybe it would help to talk to the person that was supposed to give you the item in question and ask them casually “hey remember…” it might help you see if you really forgave them or not to talk to them about it.