@Kerstin http://en.wikipedia.org/wiki/Bruxism It's a thing. And quite a serious issue. Especially if you're stressed out about something, but aren't quite aware that it's stressing you out.
There is a huge difference between forcefully playing a game for Gold farming and playing it willingly to ease off your stress (even if you endup raging and getting more stress. <.<)
I'm under the impression that being an artist (i wouldn't know firsthand) is very stressful work, therefore these posts seem to be a way to relieve some stress with mindless dickery. That and alchohol (amirite)
My expert medical diagnosis: I'll bet it's an eye spasm from stress. I get them occasionally. Nothing you can do except lower stress levels, or heavily medicate ;)