I have done this to all 3 of my minis, I believe the kinetic pressure against the gas block is bad if it is not square and even. I believe it helps increase the accuracy because the 1st mod most of us do is adjust the gas block screws for even pressure against the barrel. Same thought about the gas block, even the surface pressure. I have not ill affects, I use a vacuum cleaner belt for a buffer on both ends of the op rod.
Remember the battle of Athens, TN!
"Work as if you were to live 100 Years, Pray as if you were to die To-morrow." --Benjamin Franklin