Lots of urban, stop n' go driving?
Maybe 20k miles is about right for a set of brake linings.
One would suggest taking it to a shop that you trust and asking them to have a look at it. Or, you can check them yourself by putting the car up on jack stands and pulling the tires off. Have a look at the linings. If they're getting thin enough that the metal parts of the linings are contacting your rotors that explains the noise.
If you've been living right (Just kiddin' bro!) you'll get off with a regular brake job, consisting of new linings and getting all four rotors turned. (I assume your Challenger has 4 wheel disc brakes, however you might have drum brakes in the rear but the same principle applies here re stop n' go driving.)
If you drive a lot after you start hearing brake noise you take the risk of really messing up your rotors and having to get new ones. It helps that your car is new, in that your rotors still should have enough metal on them that they can be turned and still be within spec.
Good luck.
:: Maybe 20k miles is about right for a set of brake linings. ::
Uh...okay...if the dodge is a 63 Dart.
4 wheel disc-brakes are the industry standard.