I have kept ball pythons for about 8 yrs. And have been bitten a couple of times. If the snake is in good health, I don't really see any reason for worry, however, you may want to contact your pediatrician for medical advise. S/He may want to start your son on antibiotics just for safety sake. Your neighbor shouldn't be exposing children to the pet snake.
I'm sure you cleaned the wound site with an antiseptic, and continue to use neosporan on it until it starts to heal.