it is normal for the first 500 miles. If it is excessive, you are probably hitting the brakes to hard and if you continue, soon you will screw up the brakes and you will actually need to get a new brake job again!
Many people don't know that when you get a new brake job, you have to "break in" the brakes. just like when you buy a new car, you are not supposed to drive it hard and "break it in" the first 3,000 miles.