You should have annual vet visits, just like with every other pet you own. I take mine twice a year, and whenever I think something may be wrong. Really learn the body language of your bp, because they don't show distress the way a cat or dog might.
I have to respectfully disagree with you. Why would you spend the money to take a healthy snake to the vet? What purpose does this serve? What do you have done while at the vets? Is there a reason you do this or is it just to have peace of mind?