I think it just means you've placed the set near a nerve. I get a "stinger" every so often. Significantly less so now that I've set my delivery to the slower setting (Menu > Setup > Delivery - Slow on the Vibe), so definitely worth looking at that, as CarbsRok suggests. They're rarely bad enough for me to pull the set and put a new one in, but if it is really bothering you (or you're getting any signs the set isn't working correctly) that's the best way to solve the problem.