Rolex Datejust movement

[ShiamRolexBoss]

I recently retrieved my Rolex Datejust 1601 from an authorized Rolex service center after a full overhaul of my watch. For some reason, there is some "lag" in the watch's second hand (in some regions of the face (most notably between the 35-second mark to the 50-second mark), the second hand sweeps, stops instantaneously, jerks, then sweeps again (the sound of the automatic movement is constant, however)). All this happens very quickly, so quickly that you can't see it without looking extremely closely. I know for a fact that it is not a fake. Are there any reasons for why my watch is doing this?