Hi FLTATT welcome to the forum....although you hurt my babys feelings :-)
Since you say you had to lay down and crawl under the car to notice the damage for now I'd give the dealer the benefit of doubt and assume they did not know about it.
There is no cool off period on vehicles, at least not in CA, but a dealer or company "Saturn" may offer such a deal.
I am no lawyer so I can't say for sure, but once you sign and drive off the lot the car is yours. If it ain't working right or has damages you have to give the dealer a chance to fix them. There is something called the Lemon Law that controls all that.

Btw which carrier are you flying for ??? I am a very frequent traveller, so we may meet up in the air some time.