Parts of the brake vacuum system were on recall. If the brake booster had gotten oil contamination inside of it, BMW would replace the vacuum line, check valve, booster, master cylinder, & flush the brake lines. If no oil was found in the booster, BMW just replaced the vacuum line, & check valve. I do not remember seeing anywhere that the vacuum pump was replaced under warranty. They replaced everything on my car, but the vacuum pump.
As Yorgi stated, the vacuum is fairly cheap. It should only take 20 to 60 minutes to replaced, based on your skills. There are a couple of lines to be removed, & 3 or 4 bolts that hold it on. If you have a good relationship with your SA, maybe they might take care of it under the recall!