Thanks guys.
Binding was my first thought as well, but at 1000 miles from new? I guess anything's possible.
More info:
Should have added that the occilation is very smooth, almost a perfect 'sine wave' effect. If its binding, its doing it very 'smoothly', as contradictory as that sounds.
Also noted that contrary to my initial post, the magnitude of the occilation seems to be proportional to speed, and while accelerating hard, it does still occilate.