Just to echo a couple of points:
1) These will definitely stretch a bit in the waist (probably directly proportional to the amount of stress placed upon them). I've worn mine about 10 times, and they seem to be about 1/2 inch looser.
2) Anyone on the fence about them should buy; they are incredible, both in texture and color. Just in the brief wear I've put on mine, I can already see some color peeking through the black.
In short, if these are your size, you should buy them.