The truth is, normals that aren't het pied hatch with those markings all the time. It is not a fool proof method of telling if a snake is het pied. I've hatched normals with those rail road tracks that run the entire length of the belly from head to tail on both sides that I knew were not het pied.
There technically is no such thing as het markers for any recessive gene. There are however, certain traits that a very few recessive gene hets can show such as the railroad markers on some het pieds.
There are many 100% het pieds from well known reputable breeders that do not have these markings at all. The railroad markings are not always present on het pieds and they do not always mean that a ball python is het pied if the genetics are unknown..
So, if the snake was not sold as a het pied, and it's genetics are not known, until it is bred to a visual pied or a known 100% het pied and actually produces visual pieds, it is only a normal.