ROFL! Revenge! Sometimes they can be a little TOO smart . . .
A thought: if this happens every time you send him to his room after he nips you, maybe he's trying to tell you he needs to go out with his nipping.
Try giving him his "Sit" command the next time he starts the nipping. When he sits, you can praise him for sitting, then ask him if he needs to go out, or go potty, or whatever you've been using as a verbal cue. That way you've stopped his little nipping session and he's gotten rewarded ONLY when he's been a good boy and done his sit. The nipping hasn't gotten him any real reward, but minding you has, taking any excuse to use nipping as an attention getting method and teaching him that coming to you and sitting down like a good boy will get your attention every time.