We are not told specifically that Montresor has any form of psychological disorder. Since the narrator of the story is Montresor himself, we can assume that he would be less likely to see such indications within himself. Of course, a case could be made that Montresor was not quite right. He seals a man behind a wall to die a slow and painful death because of some perceived insult. The story begins with Montesor's claim that "the thousand injuries of Fortunado I had borne as I best could, but when he ventured upon insult I vowed revenge." We are never told what this insult is, therfore it is difficult to believe that Fortunado deserved his fate. We know that Montresor's family coat of arms depicting "A huge human foot d'or, in a field azure; the foot crushes a serpent rampant whose fangs are embedded in the heel" share an idea of where his attitude towards Fortunatos supposed insults stems from. We cannot be sure if this is just an attitude or if it is a psychological problem. Considering that Montresor takes his revenge to such extremes and that he shows no remorse for the atrocity that he has committed, I would say there must be some form of psychological issue at play.