Just got my screen replaced by Apple under the quality program and has been a little over a month. Just saw some stupid rainbow circles on my lock screen, when I wake my Macbook from sleep. Have attached a couple of screenshots I took with my phone. Circles appear once every 15 wake-ups. Any idea what this could be? Just read somewhere that a PRAM reset fixed it for a guy so I have done that for now. Lets hope that it fixes it.