I think you are are referring to the steering/ignition lock. Once a vehicle is jacked-up off the ground, the suspension hangs lower & sags down slightly. Once the vehicle is let down onto the ground again the wheels grip the ground before the suspension has fully settled, this creates opposing forces between the tyres, wheels & steering mechanism. These forces are normal, but they do have the effect you describe on the steering/ignition locking mechanism which cause it to bind slighlty, this is the resistance in the lock you are feeling. Basically the ignition locking pin is binding against the steering column lock which makes it feel tighter.
Giving the steering wheel a little wiggle from side to side as you try to turn the key releases the tension on the locking pin and allows easier turning of the key.