It is absolutely possible the parents can be het hypos. There are no visual markers for het, so unless the owner has the parents, grandparents, great grandparents, great great grandparents and great great great grandparents of these snakes, you cannot say they aren't het.
I can promise you they are at least het hypo. The rest is hard to say. Patterns can vary so widely, and abnormalities during incubation can cause weird patterns to happen.
It is a really lovely animal. Chances are it will only get more amazing as it grows.
Gale