Cause of sudden vibrations?

My truck has had several things done recently:
New steering rack
New upper ball joints
Tire rotation
Alignment

That was last Thursday and it's been good since, until today. I drove to work as usual and only thing I did different was apply the parking brake today, usually I don't use it. Going home I immediately noticed a pretty severe shake through the steering wheel that seemed pretty consistent from 30 mph to 70 mph.
So, what would cause a sudden vibration?

 

Check your lug nuts and make sure they are tight

 

Just do a bolt and nut check. Make sure everything is tight. could be that it was good enough, but after you driving, it backed off