Certainly a reasonable question and an appropriately written original post. It made me examine the inlays on my new 594WL and I noticed some gaps between the inlay pieces that are similar to the ones in the pics you posted. I didn't notice any brown spots on any of mine though. I chalk up the gaps in the inlays to the fact that this is very detailed work done mostly by hand with a variety of materials that aren't necessarily easy to work with. The variation is something to be celebrated in my opinion.