Some people 'maintenance' feed young snakes, to my understanding, to keep them small until they sell. I have a 2014 pastel pied male that arrived last month at 165g. I have a CH boy I got at the same time who's only 106g, who arrived at 81g. Age doesn't really have anything to do with size, to my understanding. Some grow fast, some grow slow - They all get bigger eventually. This month, that pastel pied boy is 264g. One gained 20g, the other gained 100g in the same amount of time - each at their own speed. As long as everything else is right, I personally wouldn't worry about your boy, and just keep him on a regular feeding schedule. A vet visit certainly wouldn't do any harm, though, if you have a good reptile vet in the area!

Disclaimer - I'm no expert. Just recounting my own personal experience. I'm a new BP owner, as well.