Sometimes weird stripes happen when lots of genes combine.
For example: Pastels and super pastels have zero striping, piebalds have no striping, but my super pastel piebald has a long unbroken stripe which I’m sure was not expected when the first killer pied was hatched!!!
Hard to believe you would have a visual recessive gene just spring out of nowhere, maybe it is a new morph! Probably just a unique thing when lots of genes blended.