I agree with Jeff on the possible toilet senario. If that fails, you said you are in a new home, you may have high pressure as well. If after replacing the fill vave (ballcock) of the toilet, you still have rattling, try installing a couple of shock absorbers on the water supply lines under the bathroom sink. They make them that install in the same location of the angle valves under the sink. Fairly easy to install. Some new homes and new areas have high pressure 70 to 85 PSI most homes work best at 65.