I get mindstate-related twitching sometimes, though not to the degree you're describing, and I'm not entirely confident that it's the same phenomenon.

In my case, the mindstate-part that correlates with twitching is very subtle. I wouldn't expect someone who's unfamiliar with closely observing their own mind to be able to notice it at all.

If anyone wanted to replicate this experience they could do so by withdrawing from Effexor (or, I have heard, Paxil). It is, shall we say, novel.