Funny you should mention it- would you believe that in just the right daylight condtions, the worn "edges" of my Stealth actually shows a purple/black color!
I was wondering if I was the only bongo owner who'd notice the neck of my instrument had turned glossy (after 1 year of pretty intensive use). Maybe it has also something to do with the acidity of one's hands...
Do your new strings turn flat quite fast ekb16b?