It's possible this happens for the same reason it happens on many of the Fanatec wheels prior to the CSR Elite and CSW. What happens on them is that if the wheel sits for a period of time in one spot, it warps the belt right where it goes over the pinion gear on the motor. Because this is such a small gear, the belt makes a very tight turn. After some use it goes away on the Fanatec wheels.
It's possible that the same is the case with your wheel. Maybe it just sat in the box for a long time. Maybe it was in a really warm location when that happened, making the belt more susceptible to this.
I can't know for sure, it's just a thought based upon experience I've had with the Fanatec wheels. I finally started leaving my sit in an off center location when I was done each time, that prevented the issue for the most part.
My new T500 is coming in the mail this Wed... It will be interesting to see if it exhibits this same behavior.