Most blizzard corns will retain at least some coloring, though faint. Usually it is either confined to the head/neck region, or it shows up in a pattern so faint as to be almost unnoticeable in adults. Some blizzards are pure white all the way, but that is rare. A tid bit of color cropping up is not that unusual at all.
Of course, that is just from my experience. A couple of years ago I had four blizzard corns. Two had a very faint pattern that could be seen over about 3 inches of their backs as adults. So faint that it had to be in just the right light at the right angle to see it. And the other two were odd. One had pink along its chin, but no pattern. The other had a touch of yellow on the sides of its tail, but no pattern.
Anyway, from my understanding, even though blizzards are supposed to be "pure white" , they might still retain traces of color or pattern. As long as it's not an overwhelming feature of the snake, I think you're safe.
Dave.