If it's just a tiny darkish fine line just up from the vent a little ways, it's just the healed umbilicus that once attached your baby snake to it's nutrition source inside it's egg. Eventually it pretty much disappears but it's very commonly seen in young bp's.
okay that sounds good. should i take him to the vet in a few weeks to get a check up to make sure he is healthy? and how much do you think it would cost?