Cadillac Repair: Cadillac Deville Suspension and Brakes, new car warranty, cadillac deville

Question
2001 Cadillac Deville 4.6L V8
The car was purchased used a week ago with only 32,809 miles. It has a new car warranty offered by the dealer because of the low mileage.
The brakes would vibrate when used and the check brake fluid light comes on at times. The dealership turned and machined the back rotors. They said that all the brakes had been replace on the vehicle. The check brake light is coming on again.
Is the rumbling, humming noise that they say is coming from the suspension system normally audible inside the vehicle? I was told that it initiates when there is a weight shift, but I hear it backing up, slowing down, etc. I would like to know if this is going to be a future problem with this vehicle.
Thanks

Answer
The rumbling noise is most likely caused by the wheel bearing in the wheel where the noise is coming from and needs to be replaced.

The check brake fluid light is most likely caused by either LOW brake fluid in the master cylinder and or the switch is faulty at the master cylinder.