I think RIOT made a mistakes on my TFT ranks

I played 4 TFT ranks. In the beginning, my rank was Golden 1 64 points, and after that, my victory was fifth, second, seventh and first. After that, I should be promoted from Gold 1 to Platinum, but Riots deducted me an additional 29 points, which caused me to stay at Gold 1 84 points. Does this happen often and what should I do?