I think that this is common problem with D90. I also own 18-105 and didn't notice the backfocus, because slow aperture. When looking really carefully those 100% crops, you can see the backfocus even with that lens, especially in tele.
I also tought that dx-lenses could solve this, anf problem occurs only with screwdriver lenses like AF-D primes, but no. My beloved Nikkor IF-ED 17-55G SWM DX f2.8 did the same!
I'm now happy owner of D700, as much as loved D90, D700 is so much better in every ways.
Just tune that micro-focus setting more, you will get it right!