I just ordered a used Oly 25mm 1.8 via B and H. The lens was rated as a "9+" condition. My Question Is: What should I look for to make sure I have a "good" copy? (I can return it within 30 days) I see folks on the forum talk about lens centering quite a bit. How do I make sure my lens is centered? Are there any other things to watch for in a relatively new lens? (I'm sure there won't be fogging/weird rattles/etc.) Thanks!!!