Yes, it does sound anal!
I wouldn't ride a bike in the rain, unless I happened to get caught in the rain, then i'd ride to the nearest overpass or cover and wait it out.. but that's mostly because rain tends to make roads slick, and when you're riding on two skinny wheels at 55+ MPH it dosen't take much to biff.
That, and I don't wear a full face shield when I ride a bike.. and raindrops hitting you in the face that fast don't tickle!
But a truck has a roof and windshield wipers.. it's built to drive outside.. I can't imagine what harm getting it wet would do.. I mean.. how do you wash it?