Originally Posted by Retro Grouch

I've worked on lots of bikes that had improperly dished wheels. That would drive me crazy. The fix is to loosen all the non drive side spokes 1/2 turn and then tighten the drive side spokes 1/2 turn and repeat the process until it's centered. If you are careful and precise during this process, you shouldn't have to do any additional truing afterward.

To answer your second question: Since you noticed, now you have to fix it or, like me, it will probably drive you crazy too. If you hadn't noticed it, you wouldn't have to do anything about it.