7D: AI Servo "stutters" on static subject

Hello all,

Trying to determine if my 7D's AF is acting up again…

I was testing a new 15-85, and I noticed the AF wasn't consistent at the WA setting part of the time, seemed like it was slow to acquire AF as well. With the camera on a tripod, just for kicks I used AI Servo on a stationary subject. While I was holding the shutter button at half-press. the camera/lens was struggling to lock focus, resulting in a tiny "stuttering" that seemed to get worse the longer I held it. I also did this with a 17-55 2.8 lens as well, and the same thing happened. Naturally, some pics were in focus, others were OOF.

Anyone else try this, and would it be considered normal?

I would like to mention that I did this test in less than optimal lighting (a living room with incandescent table lamps), the camera has version 2.0.3, lenses wide open, ISO 400-1000, center point and center spot AF. C-Fn's for AI Servo are at their defaults.

Thank you all for your comments, greatly appreciated.

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-Dave G