Hi there - I have a 2017 American Special tele that I bought new, and I am wondering what these off-color dark marks are on the edge of the fretboard. They are only present from about frets 4 to 8 and it doesn't feel any different. I assume it's not wear as this is a pretty new guitar, but is there something I can do to stop this from happening? I want this guitar to last. They aren't exactly visible when looking at the neck directly on its side. Any help is appreciated, thanks!