It is a cool project, but I think the jury's still out on whether it should be called a "Silver" or not. The problem is that so many people have found interesting wild subocs and cried "Silver, silver, silver!!!", when, come to later find out from an expert, they were actually "Gray" phase subocs.
The difference is in the genetics, and usually in the color also, but through multiple additive alleles, selective pressure can create several versions of the same basic phenotype with different genetic backgrounds. There are about seven or eight different "Gray" phased animals in my book from various localities, and their phenotype is most likely an example of polygenic inheritance.
You can usually see the difference between them and true homozygous recessive Axanthics. I tend to think that Aaron's animal is either an extremely gray animal and a product of polygenic inheritance or it could be a new recessive trait that hasn't been proved yet.
The thing is...with Axanthics of most species (all species, in fact, that I know of), the trait is simple recessive and the Axanthic suboc babies are silvery blue right from birth. They don't "turn" into silvery animals whatsoever...they're born with the phenotype, and their Steel Blue color is, to me, quite different from any of the Gray phased animals.
The Gray phase do, however, ontogenetically turn more gray as they mature. That's why I think this could be a Gray animal. There's also a different photo of Aaron's snake in my book on page 69, and it looks dingy gray, not Silver, like the Axanthics. But I hope I'm wrong...an Axanthic Black Gap would be killer!!
It's certainly wicked cool whatever it is.
Here's a pic of Aaron's that he took.

And here's a pic of a Normally-patterned Axanthic (aka Silver) baby with two siblings, showing the difference in color from the first photo.

Dusty R
Suboc.com