This is most likely the problem. It happens when I mill lumber on my bandsaw mill if the blade gets duller on one side than the other, especially if...
No finish is needed, but if one is demanded then I think the best option is food grade mineral oil. It won't prevent staining but it won't impart any...
I was reading about Milesi finishes and they referenced coffee as being a problem so I decided to test a subset of the finish specimens for reaction...
Prashun, you should do it again with an hour of exposure to keep it consistent with what I did. That way, if it comes out good we'll know it was due...