Holy cow, that's fast. You must be feeding it well.
I had thought it was older, but Seadation and I tentatively dated it back to 5 years old from seed.
Either that or there is a mistake in his records? My guess it that there is a mistake.
I did some research through old photo's and text. Confirmed my tree is in fact a 2013 seedling. Seadation gave me the small seedling August 3 2013. I planted it right away in ground. It is in an area of my yard that has better soil than the rest of my yard. In an area where the previous homeowner kept pigs and chickens, topsoil is black, and gets irrigation. It is planted between 3 mango trees and a Mulberry, getting 70-80% filtered sunlight, 20-30% direct sunlight for most of its life. I give it some slow release fertilizer, and occasional foliar sprays of the "Patrick mix" ( chelated Iron, Southern Ag citrus spray, occasionally mixed with foliage pro).
Obviously it is happy where it is planted. Seems like a synergistic effect of proper sunlight, water, food, and genetics.