I don't know where you get your information from, but not all het pieds have the tracks. And the lack of tracks would not mean they snake may be 50% het pied. 50% het pied doesn't mean its half het pied. It means, the individual snake has a 50% chance of carrying the pied gene. IF we use YOUR logic, if the animal does carry the pied gene, it would have tracks. And if the animal has tracks, then it MUST be a het pied and therefore would not be only 50%.....am I making sense? This is why your logic about hets doesn't make sense.
IF her snake is het pied, the ONLY way to find out is to breed it. Tracks or no tracks, it might be a het pied. Or it could have tracks and just be a normal. I have seen het pieds without tracks, and het pieds with tracks. With simple recessive hets, there is no GUARANTEED way to know if it carries the gene or not unless you bred it yourself and know the parents or you breed it. There is no physical sign that says "This is a het." if it is simple recessive.
To the OP, you have a nice normal and I hope it proves out het pied for you, but you won't know until you breed it. And the snake is not a yellowbelly either.