Yep, stress can certainly cause this, as can eyestrain. If you spend a lot of time at the computer, you might try to give your eyes a break every hour or so by focusing on something far away for a few minutes. Also, make sure you are getting enough vitamins. Certain deficiencies can cause muscle twitches. I sometimes get an uncontrollable twitch under my left eye that is very pronounced, but that is just a remnant of a condition I had years ago and it will probably always be with me (and that's definitely not what you have here).