I'm hoping somebody could answer my question. I have the possibility of buying a used panny 25mm from a friend of a friend. I've used it and it the photos it produces are amazing. The body and optics seem to be perfect, but I've noticed some slight backward and forward play in the focus ring (fraction of a millimetre). Is this normal? None of my other lenses do this. I guess I'm worried that this might be sign of something about to go wrong! Any advice would be greatly appreciated.