I've had the same problem with the right rear center cap. It's fallen off for the second time since I've got the car. When I go to the dealer they tell me it isnt covered. I think this is bullcrap. What should I do because the center cap feels really loose in the hole and doesnt really snap in like it should.

My suggestions:

1) Buy 4 center caps for a 2004 Monte Carlo SS (they have the outline of the bowtie in red), ship them to me, and I will send you all of mine.

2) Buy a new cap. It shouldn't run you more than $20-$30.