scale rot 99% of the time is on the underside of the snake. From the looks of it, it just looks like a out of place colored scale. I have my female albino who has one scale that is tinted brown. Just keep eye on it but to me not scale rot
If you notice brownish scales on the belly then its time to look at the husbandry. For now keep him on newspaper or paper towel. Just for a precaution