Do stepper motors require any maintenance? I've had my printer for almost a year now.

Is there something I should be doing to maintain the motors?
The stepper motor itself does not.  You may want to inspect the motors for debris or dust.

Depending on your configuration you may want to check on parts of your printer that connect to your stepper motor such as shaft couplings, pulleys, lead screws/threaded rods and belts.  The stepper motor wires should occasionally be inspected for wear and strain.