I, too have noticed something similar. I'm not poo-pooing the observations of the makers and wearers who responded previously, but I can't explain away my change in fit by citing weight loss. I've owned my well-made 8 yarder for about 7 months but worn it many times. I started out right in the middle holes, but now I'm right at the smallest adjustment. No weight loss (if anything, I've gained weight!) or shape change around my midsection. Bizarre.

Like I said, the kilt is very well made. It is 14 oz Welsh wool, which has a much softer feel than other kilt wool I've felt. Don't know if that makes a difference...