If you don't want snails in your tanks, take him out. Easier to remove 'em before they fully infiltrate (although the bad news is that if you see one snail, you've probably more, or eggs, elsewhere in the tank).
Personally, I like snails and consider them a valuable asset in my tanks. Even those dreaded malaysian trumpet snails. And, yes, sometimes conditions occur in which their populations boom--in which case it's just one more of those balancing acts that make keeping aquariums challenging and fun.