Many scholars would claim that Joseph's sin was hubris. But by careful considering their interpretations, I gathered they are heading the wrong way, minor, but not the least.
I do not believe that Joseph sinned by "showing off" all his blessings. The other side to this might not necessarily be humility, but hypocrisy and fake modesty can easily be mistaken for humbleness.
Nevertheless, I believe that Joseph wasn't all perfect. I would need further study on this issue. Just as many would think that Job did not sin. But by his inquiry to God, he has sinned. Some would say that he confessed for his original sin, but I do not believe that is the case, for God did not ask him to confess for that sin, it was the confession of belonging to a fallen ancestry that God wanted him to confess.[@more@]