This is either because the new spring(s) changed the ride height or the new spring(s) has the center pin in a different location.
Did you change 1 spring or both sides? Check it out to make sure the springs are the same and that one is not installed backwards. Given that everything is OK with that, adjust the sleeve on the drag link to bring your steering wheel back to center.
If you changed the height of the truck, make sure you corrected the angles. The drag link should be horizontal when the truck is sitting.