Hmm thats not good. It sounds like a input shaft. At any rate, that should not be happening on a brand new car with less than 1k miles on it. Hell you should not be hearing that with 20k miles on it !
Now if I wanted to poke fun I would <insert here> something about GM QC
...But being a car lover, its just not right that anyone would or should have to go through this with a new car. Does your state have a lemon law ? You may want to look into it as a last resort...Your dealer should be doing something about this.