no, it should be fine. I wouldn't be convinced it will be btter than the stock cooler master stuff, but even if its worse, it won't be by much.
thermal compound really doesn't make that much difference. I used to use bulk stuff from jars that were used in electrical companies for their internal voltage regulators. the stuff looked like grey slop. when i switched to mx2 eventually, i only saw a temp drop of about 3 degrees.