2002 Honda Accord Noise following timing belt change

Just had the timing belt and water pump changed on my 2002 Honda Accord. I took it back to the repair shop because my wife and I noticed that the motor is much louder now. The noise seems to originate from the water pump area. The mechanic said that they put the timing belt on with a little extra tension so that we wouldn't have to bring it back for an adjustment later, and that once the belt gets "broken in" (in about a month), the noise will go away. Is that true? I thought that the purpose of the tensioner was to take up the slack in the belt as it stretched, meaning that it wouldn't have to be over-tensioned when installed. I'm suspicious.