Seamus from Sportkilt got back to me right away and said they have used fabric from different sources, over time. My Sportkilt is apparently done up in an older material, that may have been a poly/acrylic blend. Since the time I purchased mine (2009) they have moved to a PV that has an anti-pill finish.

He offered to replace my pilled-up kilt, but said it would be made from their last remaining stock of the older fabric. I think that is fair and I'm seriously considering the offer... what great service