I would definitely say that it would depend on whether or not you want to own your own business and what type of masonry you want to do. If you are looking to own your own business, I would suggest some business management classes. If you are looking to do masonry in terms of decorative stone work and things like that, I could make the suggestion that you might want to take a few architecture classes just to get the knowledge of it under your belt. Other than these two instances, I cannot off the top of my head think of a time when you would need any other education in order to do masonry work.
Hope that helps and good luck.