Steering wheel twitches when I turn on engine?

[Reyals Bemus]

I have a strange little issue. Its not really a problem, just kind of an annoyance. I recently installed power steering on my '64 panel. I used Captainfab's adapter plate (very nice by the way) and a reman '86 gearbox. I ran the correct lines and the overall installation went smoothly.

Whenever I turn the engine on though, the steering wheel twitches to the right a half inch. That's it. The power steering works wonderfully. Its very smooth and positive feeling. I'm just wondering what's causing the wheel twitch on start up. None of my other old Chevy's do it..?