I have the same noise and it is not normal. I can recreate the noise by driving under 10 mph in first gear, press in the clutch pedal and CLACK CLACK CLACK.
I took my buddy(a GM Powertrain Engineer) for a ride in the car and demonstrated the noise a few times. He confirmed that the noise is not "normal". There are several TSB's related to the clutch that may be the cause of the noise. I plan on taking the car to the dealer soon.