DEFINATLEY take it to the dealer. My X did the same thing with around the same mileage. It took numerous attempts to find the exact problem. They eventually replaced the whole steering collum and joints. They told me that the car was not safe to drive and that the steering was somehow deteriorating. I think they said it was unsafe because of liability, but reguardless it had a major problem and they repaired it. My problem was exactly the same as yours. But def. take it to the dealer, I think they have a bulletin on this issue.