When you stop your vehicle, if the wheels are turned in such a way that there is pressure on them to return to center, or against a curb, etc. it can put a lot of presure against the steering wheel lock (part of the ignition key mechanism).
Most of us have had it happen. Once you realize what is happening, you deal with it (either by moving the steering wheel to reduce pressure on the ignition lock or parking without side pressure on the tires.)

 

I've had it happen in a 1975 MG and a 1987 Toyota Corolla.

 

I'm still driving my '87 Corolla FX, do you still own yours?