Same thing. Mine is almost 2 years old and it just started. I posted somewhere else what to do but to recap quickly. Send it to apple let them try and diagnose. If they can't see the flicker and won't fix it, speak to a senior supervisor and express your frustration because it's an "intermittent issue" and get them to override a repair. If they do see the issue let them try and fix it. (Most likely will replace logic board). If that doesn't fix it, speak to the senior supervisor again after getting it back, refer them to the hundreds of people here who are having the problem, and the online youtube clip demonstrating the issue, say you cant afford to have your computer shipping back and forth and most likely they will offer a replacement. That's what they did to me. Haven't done it yet though because waiting for them to release the update before I get my new one. Also, be POLITE, do not be an ****** or you will get nowhere. Calmly and kindly express your frustration and you will get what you want.
