It wouldn't be something as simple as pressure on the steering wheel, would it? Occasionally the steering wheel is left cocked when I park which results in pressure against the wheel lock. The key won't turn until I turn the steering wheel slightly in the opposite direction as I start the car.
The AutoZone technician the other day went out to run a CEL code. He couldn't get the key to turn and after fumbling with it for a minute or so he let me try. I knew what it was and corrected it right away. I won't say bad things about those AutoZone guys - at least they provide a free service.
