picked up my 2012 Mustang GT Wednesday night and been driving it quite a bit. however, starting today i noticed a single ticking noise coming from somewhere when i apply the brakes. it only happens when i apply the brakes and goes away until i reapply the brakes again. it is a single tick, not continuous, and happens at any speed it seems. more noticeable at slower speeds however. any ideas on what could be happening here? anyone else having this issue?