Yeah, this one's common. You're probably hearing it from the chuck when you move the tool, and it's almost certainly fine.
That ratcheting sound is part of the spindle lock feature. It's designed to do that when you open or close the chuck by hand. It doesn't indicate a problem. If you're hearing it while the tool is just sitting there, you might have bumped the chuck sleeve.
If the noise is coming from the motor area when you pull the trigger, that's different. First, check that the control switch isn't in the locked (center) position. If it's in forward or reverse and the motor makes a grinding noise but doesn't spin, stop immediately. The gear case could be damaged.
Heads up: Always let the motor come to a complete stop before using the control switch to change direction.