I have the exact same problem. I've taken it to a local alignment shop and the dealer, probably 4 times in all. They all assure me the 4-wheel alignment is perfect. The car tracks straight, but the wheel is very obviously not centered.
I thought at one point that they had simply failed to center the steering wheel, but I brought it back and they spent an hour re-centering it, and when I got the car back it was exactly the same as before.
I do have some unusual tire wear - I hit a large rock on a road trip and then drove home for 1,000 miles without getting the alignment fixed - so I can't rule that out as the cause. You can see the uneven wear looking at the tires but it is hard for me to believe it causes such a significant effect.
In a few months I will be due for new tires and I'm hoping that fixes it. It does drive me nuts.