sorry, no complaints here.....i don't have a black G6, however.
have you asked the dealership if anyone there had 'buffed' it or put any kind of "Paint Sealant" on it before you took delivery? i can't say that i have EVER seen a car straight from the factory with 'swirl marks' in the paint, and i've been in the dealership business for 20+ years.
maybe the car was on the lot for a time and had some foreign substance on it (tree sap or bird doo doo). sounds like an inexperienced detail person that cleaned up your car may have done you an injustice.
again i suggest you contact the dealer and if their response isn't satisfactory, ask for the Pontiac Reps name and number.
DON'T SETTLE FOR LESS THAN YOU EXPECT!!!
good luck and let me know how it goes, ok?