A99 Soft focusing issue?

Does anyone noticed that the AF lock tone goes off before the focusing actually stops?

Like it will Beep and you will still hear the AF motor adjusting.

I did a few stationary tests to see.

I noticed if I took 10 shots of the exact same thing, 7/10 will be in focus, and the other 3 will be slightly "soft focused"

The soft focusing almost always occur when the lens continues to adjust right after the beep goes off.  Like it will lock focus, and it will move a little more.

I noticed that this usually happens on low contrast areas.  Like it will nail focus the first time but makes smaller adjustments which throws the focus off.

Not sure if its my body or lens?

Thoughts?

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