Then it was probably nothing to worry about in the end. Sliding around in parking lots is fine and won't hurt your car unless you hit something, usually, so don't worry. You probably hit a crack in the pavement or your tires may have caught too much traction for a second, but I doubt it was a mechanical problem.

 

Wait, is the problem persisting even after the drift or was it just during the drift?

 

On Tuesdays following a new moon when it's foggy?

 

If you were drifting and it was "bumping" it could've been your rev limiter kicking in at redline.

 

Or maybe it wat the famous "FRONT END CHUCKLE" TSB problem.
Crappy OEM upper strut mounts.

Or has that been ruled out as a possability, Mr Radioactivity?