The first obvious call would be a sticking king pin, however since you just had the wheels off, watch out for zebras.
How did you jack it up? How was it supported for the work?
Any chance of a bent tie rod? R&R steering arms?
Wheel bearing didn't seat properly?
The check for king pin is easy. Jack up front. Unhook the drag link and grab one tire and try to swing the wheels in and out. Moves easy, not kingpins. Moves hard, pop 1 tie rod end off. Try each wheel. one easy one hard, bad kingpin.
While the drag link is off spin the steering wheel and and see if it feels tight.
