Mitch, remember that this is after just 7-8 trips out. Either there is something wrong with the sheet itself - unlikely, but not impossible - or there is somewhere that's chafing it.
Yeah, that's the same for me. Ours had a surprising amount of fraying after our first sail in heavy winds, but it appears to have stopped - or at least moderated - for now. I know that some lines can resist fraying better than others, either due to quality or material differences.
My folks had a 26 foot monohull for the better part of two decades and we had the same issue with the jib lines on it. The mainsheet was fine, but the jib lines required close attention due to the fraying. What we found over the years - after replacing the jib lines on a regular basis - was that the cam cleats were the culprit, especially when the jib was under heavy load. We also found that slipperier lines would chaff more than lines that weren't as slick feeling when they were brand new.
I think the same thing is happening with the TI mainsheet. When we first got it, the new lines were so slippery and harsh feeling that I had to wear sailing gloves every time we went out in anything over 5 knots, as my hands would get torn up by the line. Now that it's frayed, it's easier on my hands and I don't have to wear the gloves. And as I noted above, the fraying seems to have moderated for now.