Hello and thank you for using justanswer, I'm Joe and will do my best to help you.
Assuming there is nothing mechanically wrong with the car, this is a normal function that all cars have. The wheel locks when key is removed to help prevent theft. As far as it being hard to unlock, I have seen this before. Usually when the car is parked with the wheel turned one way or the other this will happen. If parking on an incline it can make it worse. I can suggest that when you park, try doing this in order.
1 When you come to a stop, put the parking brake on, and then put it in park.
2 Make sure the steering wheel is in the straight ahead position, so there is no load on it.
3 Take your hands off the wheel and remove the key.
This will ensure you that the steering wheel will easily unlock next time you start the vehicle.
Since submitting my question I did some research on the internet and found that there is a problem with the steering wheel locking on 2011, 2012 and 2013. I have notified the dealership. Thanks for the answer I will try it.