You should bring your laptop to the Apple Store and maybe they are going to change for you the GPU card for free. I had the same issue and I went to the local apple retail and they changed for me free. And I am not having any issues from that time.
Yeah, I'm debating whether I should go through the hassle of it all. I have already gone to the Apple Store in April of this year to have my MBP checked out. It failed the VST diagnostic and they quoted me a price. I couldn't afford it so I left.
I could insist, but, insisting is of poor taste. Or I could luck out and perhaps, they will do it for free this time. But, I am still wary how a new but the same GPU could magically cure the issue. And then, of course, a new, different issue could arise down the road, especially since Apple no longer manufactures these logic boards and I would have to go thru it all again without the assurance that the next swap will also be free or if there will be a fee the second time around. sort of like, the first one is free and the second one is not sort of thing. i think that is a street saying dealing with stuff not electronic.
I wish apple would give you your old logic board when they replace it with a new one so, in case, the new one fails down the road, one has the old LB as backup.