Steering Wheel Shudder

[Burt]

I've got an a minor issue with my steering I'm trying to troubleshoot. At low speeds (10-30 mph) once the car is fully up to temperature, and the steering has been used quite a bit, such as crawling through a big neighborhood, I start to get a slight shudder/vibration through the wheel whenever I turn it. Not enough to degrade the steering, but it is noticeable. I had a similar feeling (although to a much greater extent) whenever I autocrossed my Impala and the power steering pump and fluid got hot. I haven't autocrossed the Camaro yet, so I haven't seen how it responds when really put to work, but it does feel like the beginnings of cavitation due to heat soak. I've checked the power steering fluid level, and it's in the hashed area, so it's not due to low fluid. Anybody else experience this? It's a 2012 SS, so it's the last year of the hydraulic steering.