It´s probably either a rocker beating on a valve or, and that´s my guess, a valve clicking on it´s seat. It´s not very problematic unless the clicking gets not louder within a short timespan.
The Bullet has hydraulic valve lifters, that´s why you don´t have to adjust the valve´s play regularily. When these lifters age and don´t hold up the necessary oil presure, the play may get too big and that causes this clicking sound, just as in older engines when the valves weren´t adjusted correctly. I´d have your dealer have a look at it, he knows better how to check the lifters.