First thing that came to mind was incubation temps. You would have to have some kind of visual snake to make it a codom or dominate gene and a pair of hets to make it a simple recessive(which is very slim odds you lined up hets from two different blood lines on accident). Also, hidden genes normal take other morph genes to play out. On the other hand, if it is a hidden gene, you are well on your way to making some nice crosses though. Congrats and good luck.