Ever try to hang from a pair of smooth metal poles?
I say: Live with it; try to find a way to wrap and cinch to reduce slipping. Or back wrap. Pulling tightly to barely stretch the strap and then putting a wrap on that may help. As someone who regularly cheats and uses adjustment of the location to tune the length, I'm familiar with variation between trees in the ease with which this is easy or hard. Polyprope stapping is always easier....and it degrades through tearingand abrasion more rapidly than fully speced seat-belt webbing.
But, there's nothing wrong with the strap, and I wouldn't think to abrade it in order to make wrapping easier. I wouldn't think to deliberately abrade Dyneema or any other line, and Dyneema is far more slippery.