This isn't a typo, but it's a rather awkward anomaly:
On p. 15, at the beginning of the Connie wedding scene, Don Corleone is described thus: "And the guests so exclaimed at how well he looked in his tux that an inexperienced observer might easily have thought the Don himself was the lucky groom."
But by pp. 45-56, when the Don and his family are at the hospital to be with Genco on his deathbed, Dr. Kennedy "...was surprised when the wife and daughters [of Genco] turned to the short, heavy man dressed in an awkwardly fitted tuxedo..." Musta been a long day for the Don.