Snakes have their own reasons for not hanging onto you, it's up to you to decide what it means. Some are curious, yes, but a snake that doesn't yet trust you may also
not want to hang on & try to go where it feels safer. Some snakes are naturally better climbers & thus better at hanging on: rat snakes (having a long thin physique)
are practically MADE for climbing trees, while heavier bodied snakes are more terrestrial by design. In general though, younger snakes are still learning, so even
in their enclosure (where they presumably feel safe) they're more apt to fall...sorta like toddlers.