It's very common in the fading lines. Sometimes they do keep that marking on the head and the rest of the body will be interspersed with the occasional pale tan fur or pure white.
If mine are born with any white on them they never stay that way. They get all sorts of weird markings.
I did get one of the fading lines from Ronda when she sold out, the youngest was marked beige and was pretty pale when I got her at 6 months old and her 10 month old sister was pure white. Now they both are. Very excited to play with this line.
Edited to post a picture of my girl at six months. She is now a year old and pure white.
Edited again to say that "Fading lines" means regular whites that fade with age. Nothing special here.