Could it be a het green burm? I remember green being one of those "recessive" mutations with co-dominant tendencies. I thought they even had a name for the het greens where just one copy of the mutation seemed to reduce the size of the dark blotches relative the light area in-between making an overall lighter colored snake. Was that "cinnamon"? It's been like 17 years since I had one so I could be way off for sure. I seem to remember the same sort of thing with some het granites having what was called a puzzle pattern with more irregularity than normal.