This will happen periodically, just as it did on your previous nozzles. How frequently this happens will depend on your water quality.

Accessing the Silver Plate

Unscrew the black end cap from the face of the showerhead. Tip the plate out of the cap, making sure not to lose the rubber ring.

Dissolving Buildup

Soak the silver plate in distilled white vinegar overnight once a month (+/- depending on your water quality) to eliminate any calcium buildup that can cause random sprays. Scrub with an old toothbrush under running water to clear any leftover sediment. 

Reassemble the Spray Nozzle

Place the silver plate back into the black end cap with the logo facing out and then the rubber ring with the lip facing the spray nozzle when you screw it back together.