D7000 with 18-200 VR II lens auto focus calibration

Hi All,

I am new to Nikon and the D7000. I am currently trying to figure out if I have a back focus problem. I used the guide at the below URL to do my test and found that even though the issue is there its very minor. I adjusted the AF point to -10 and seem to have corrected the issue.

http://photographylife.com/how-to-quickly-test-your-dslr-for-autofocus-issues

My question is that is this normal to have to correct the AF points for the 18-200 VR II lens or if this is really an issue with the camera? I don't have any other lens at this point to test on but I will be getting the 35mm 1.8f soon. Logically if Nikon provides this ability in the menu does mean that it tends to occur and is normal but I didn't really expect to have to do it nor did I ever read about such issue in the Sony DSLR that I previously owned. So how should i pursue this? Should i return the camera and get it replaced while its still under the 30 day warranty or should i learn from it and think of this as calibrating my camera?

- Ken

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CAMERAS : Sony A200, Fuji F30, iPhone 4
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LENS: Sony 1870 Kit Lens, Minolta 70-200 3.5-4.5 Lens, Minolta 50mm 1.7f prime lens