I agree, take it back to the bike shop and let them adjust it. Sometimes it is a minor defect in the brake and by letting them deal with it they can make the judgment call of a warranty issue or not. Also, sometimes it's just a matter of minor adjustments to get through the break in period. The bike shop should not mind doing everything they can to get it dialed in just right. Not bad brakes, just what it takes sometimes to get them dialed in.