Sigma 17-50 f2.8 focus issue (with sample)

Though the Sigma 17-50 f2.8 mostly has excellent reviews, there has been some mention of some focusing issues with this lens (as with a few other Sigmas).

I believe that I've landed with one of those bad copies and I'm having it exchanged.

Here is a sample from this lens-

Apple 1 needs to be in focus, but note that apple 2 and leaves around it are in focus.

I believe the issue is similar to Sigma 120-400mm issue mentioned here-
http://tayeb.fr/wiki2/pmwiki.php/Main/TelezoomAndTelephoto

His sample image with the issue-

The problem does not happen all the time though.

I'm curious to know what you folks think about this. I am expecting that I might hear back that I need to have my lens/camera calibrated. But reading the review above, there is no guarantee that the issue might be fixed if I send to Sigma and besides my 30 days of return/exchange window will be up soon.

Cheers.