Got back from a short 50 mile ride this afternoon and was wiping down the bike when I noticed an oil drip on garage floor. There is a vent or possibly a drain line on the left side and just forward of my Vintage’s rear wheel that the oil came from. Where does that line come from? It was getting close to dinner and I didn’t have time to trace it out. Can anyone tell me what the line is for and more importantly is oil dripping from it a concern?