People are sleeping on those knives. Kobayashi‘s grind is one of if not the best convex grinds I‘ve tried from a Japanese maker. If only the Gyuto profile was better.
I had something similar happen to me just today. I was cutting citrus for marmalade and got called urgently. The knife sat there uncleaned for 30-40 minutes. After finishing everything I cleaned the knife and noticed a weird layer. It looked like the polish had changed and but no red rust...