Hi,
Mine is a MacBook pro 13" with retina display (and just a little bit of background information i have had to have the screen replaced due to a widespread issue amongst the specific MacBook pro's- there was a repair programme put up for this even though before the programme was put up i tried to replace the screen for free as it was within warranty but apple had refused to do this. the repair programme was only put up due to many MacBook pro users complaining about the same issue and created a website about this! Additionally, i have had random issues with the laptop switching off and not coming back on although when connect to an external monitor i could see the MacBook was switched on.
Anyway on to this issue... I have had exactly the same problem! I notice this especially when I'm watching a video on youtube for example i have little lines across the video (multicoloured) thought i was going crazy but i noticed it after the update. I would try to screen shot the issue but it happens quite randomly.
I tried the above of resetting the NVRAM which helped for a few days but then the issue came back. So after this i wiped the whole laptop and set the MacBook up as new again (after backing up my files of course). However, this has not worked either. If anyone has any other solutions then please let us know!
So, I contacted apple and told them the above issues and their response was that it most likely does not sound like a software issue but rather a hardware issue. For me this is frustrating as I have treated my MacBook with such care and after paying so much for it i would not expect issues such as this especially just because i updated the MacBook. I mentioned that the problem I was having with the visuals which occurred after updating the MacBook and the response from customer service was that after an update sometimes an underlying hardware issue that has always been there may surface...
Why should an underlying hardware issue be there in the first place if i paid for a brand new perfect macbook?
My warranty ran out in January so i have no apple care left which I also explained to customer service and they simply stated that i would have to pay for any repairs and to take it in to the genius bar.
Upon doing some research I saw that there is a repair programme for MacBook users for the issues that we all seem to be having. However...this is only applicable for the older model MacBooks (2012-2013). I have inserted the link so you can see!
MacBook Pro Repair Extension Program for Video Issues - Apple Support
The problems that the link above mentions seems to largely resonate with a lot of the MacBook users in this thread.
I can also see that over 200 people have the same question too. For this reason I propose creating a website of some sort, like 'staingate' if Apple is not willing to repair without charge. As i do not intend to pay for repairs when there has been underlying issues with the MacBooks that was not our fault in the first place.
Sorry for the long message (first time posting!). Please let me know what you all think and if you have any other possible solutions.