Just out of curiousity, did you inspect the vehicle carefully when it was delivered? I went over mine with a fine tooth comb before I accepted it, and I would have noticed any minor dings, scratches, or minor imperfections. There was a minor gap in the dash where the navi meets the black plastic, and I made them align it better and remove the gap.
Lexus makes a really well built car, and the dealer should do their part to deliver it with zero defects, but some of the responsibility is yours. If the paint chip on the hood was there when the car was delivered, then it really should have been brought to the dealer's attention at that time by you.