4x4 front hub bearing- concern?

So I finally got my truck running. Been sitting since winter in garage while I swapped out the engine. Drove to the dump today and on the way back we smelled something burnt (kinda electrical, kinda rubber, I know they are different, seemed like both, could also have just been in the air but) when I park in the driveway there is light smoke comming from passenger front wheel area. I peeked my head behind the tire and it wasn't the breaks, it was m poo re the hub area. Unfortunately I had to get the kids in and fed so we could go to my son's soccer game so we took my wifes car and I pulled the tire off and the rotor off... I guess it could be grease from the ball jount runningdown the arm getting hot from the hub.

Anyway so the question. Its a sealed bearing hub assembly, there is no noticable noise on road or noticable grinding or noise turning it by hand, would you just keep driving on it and see what happens, i'd hate to spend $100 on something that aint broke, or would you replace it.... do these commomly go out. Its a 97 I just bought from original owner I don't have much history with it yet.

I wouldn't think it would be the hub bearing. Both the front ones on my '05 went bad at around 60,000 and I was told that was highly unusual (I'm attributing it to the previous owner since I bought it at 54k miles). I didn't smell any burning, I just had a vibration and a noise that sounded like I had 35" mud tires when I got above 40mph. But mine is 2wd so maybe it's a little different for the 4X4's

Dodge Sucks, Chevy Swallows

I would expect unsmoothness and noise if a bearing was going out too. But if the breaks arent rubbing and making excess heat then what the hell is burning just inside the tire