went wheeling...now vibration/ hum

Well, I went to a place I go to all the time. Nothing really new. A few scrapes and bumps on the skid plates. The lockers operated flawlessly. On the way home from the park I noticed a hum and vibration through the steering and pedals. Very faint that gets worse the faster I go. So this afternoon I set her on jack stands and put it in gear allowing the tires to free spin to see if I could see replicated vibes. Even in 4 high. Nothing. Of course I couldn't get the tires up to highway speed on the jack stands. I should be able to hear something at low speed right? I also checked to make sure all the wheel weights were still on the rims.



Any other thoughts from you guys?