Have you used magnification to look at those scales? Because many snakes do a little head-rubbing & if they happen to scrape their scales enough, the underlying skin is going to be light pinkish-white, so that may (?) be what you're seeing- it's the right place for it- they typically reach way up & rub on the top of their enclosures- especially if that's where the ventilation is too.
Then again, some snakes seem to fade somewhat- in parts of their patterns, so that's possible too. Since yours is a piebald, that makes it even more likely, I'd say.