Focus will obviously change if you rotate the focus ring. There is no exception to that.
Now, some lenses allow manual focus override even in Auto-mode, in Nikon world these are indicated with A-M (Auto with Manual override) on the lens. If your lens mechanics do not support this, you are working against the focus motor when you change focus manually in AF mode.
Also, some lenses do indicate A-M even in the User Manual (e.g. a 18-105mm Nikkor), but I noticed that although Manual focus in Auto mode is possible, it made my lens much noiser after I tried this...
Back to your specific lens: from photo.net:
SSM – Super Sonic Motor. Lenses employing SSM feature quiet, fast, smooth, and accurate focusing. All of Sony’s SSM lenses also feature direct manual focus override, allowing a photographer to fine-tune focusing without using the AF/MF switch by simply turning the focus ring.
SAM – Smooth Autofocus Motor. Lenses using a SAM focusing system feature smooth and accurate focusing. SAM is not equivalent to SSM, and does not have a clutch in the focus ring to enable DMF override.
DMF being: direct manual focus.
So as it seems, your lens does not support this. It means that if AF is on and is attempting to move focus and meanwhile you move or hold the focus ring, you are working against the motor. Whether you will damage the motor or dislocate something in the lens, no clue.
Don't use AF focusing and focus ring the same time. I would actually avoid touching the focus ring unless in MF mode.