Very funny that you're pointing this out, as I was just describing this to my wife a few weeks ago. I notice it only at low speeds (very low). As is probably true for all of us, we have certain intersections here that are infamous for their deep grooves...at first i was concerned how the XF decided itself how to navigate these areas, but now, i just pay a little closer attention and not it's not an issue.
I assumed it had to do with the tire width, since all my previous vehicles had much narrower tires.