I don't want to come across in anyway negative with this post, and completely understand and admire your decision to pass on this deer.
That said, being a wildlife science major and having learned all about genetics and inferior genes and learning a lot about deer, I would never pass a shot at a piebald or an albino deer no matter what the size. The genes that cause these are recessive and inferior and often times the physical appearance is just the start of the differences. These deer can have bone deformities, vision problems, and a slew of other issues that only that deer knows about. My schooling tells me that these deer are a harm to the genetic makeup of the herd and should be removed to keep the herd healthy.
Another thing to consider is that piebald deer are often times dwarfish in the fact that they have a shorter nose, shorter legs, and weigh less compared to a deer of equal age. That deer may have well been a 1.5-2.5 year old deer.
Just my two cents but to each their own, seeing that beautiful deer in the woods was clearly an amazing encounter and a kill clearly does not even come close to the moment the OP had in the woods that day, and that is truly what hunting is all about