Yeah, it's just weird that it didn't start making the noise until it was parked for a day. It could be a rock that came loose from being stuck on the inside of the wheel and is now trapped against the brake caliper or something.
Tomorrow I'm gonna jack it up and spin the front wheels to see if one of them is the source. I doubt it's a hub or a wheel bearing. It's a definite sheet metal scraping sound rather than a grinding-type sound I've normally encountered when roller bearings grenade and I used the 4wd to climb up on some blocks to let the water run out of the bed quicker while spraying it out, so I don't think that's it.
Meh, I'm babbling. Got insomnia and haven't slept since 10 am yesterday.
I'll (hopefully) find out what it is tomorrow when I start looking.
Hopefully it turns out to be an easy quick fix on your truck.