Hey there. Let me answer to you. It is not a bug.
37:56 [All] "This game will be saved in your ladder stats, you should play till the end."
You left in 38. minute but game ended in 52. minute. Tuskar stayed and he won PSR.
Since you left the game before the tree was destroyed, it counts as leaving the game even though autoban is off. You were not banned but you lost PSR. Next time play till end
Cheers