drivers side mirror loose

I wouldn't write it off. Take the mirror off and inspect the wood carefully and completely. Not all all mirror failures are due to leaks. Look at where the mirror is mounted. Out in the open getting blasted by the wind and every passing truck makes it worse. They get beat up out there. The manufacturers don't know how to install them, they should have a metal plate behind or in the wall for the mirror to attach to. My RV is 2 years old and my mirror decide to come loose. There was no backing behind it, wood or metal. The screws just pulled out of the wood. My only fix was doing the same thing they did, I dropped the mirror about and inch and ran new stainless steel screws right into the sidewall. Hopefully it will last longer than 2 years, what I think added to the failure was the cheap screws they used, make sure you use stainless steel.