out board lower unit ?

[Bass_Appeal]

last weekend we were out in the rough waters in the bay. headed to the hook just before the navel base , it felt and sounded like i spun my prop. so i immediately turn around before going any further from port. on the way back it seemed to catch fine, and run good ..hmmmm that odd , weird ...wth . now tonight i check the gear oil and same amount of shavings as normal... the prop hub is fine ...the prop spins in neutral without sounds of grinding or crunching. NOW here is the concern i put in gear with the engine off and tried to spin the prop an click click click click is it supposed to do that ? i put water to engine started it up put it in gear and it was spinning no clicking , then i turn engine off in gear and click click click fast as the prop was spinning ...why does it click while in gear