My bike has been sitting in our hallway all winter, doing nothing, except for my change to the WO Chubbies. I've noticed fluid running down the brake caliper on the RHS as it sits there, and dripping on to the wheel. My first thought was that it must be some brake fluid that I'd spilled when I changed the brake lines for the longer ones to suit the Chubs. But after I wiped it up, a few weeks later it reappeared. I'd move the position of the forks a little, so I still though the same, but just to be sure, I checked the tightness of the bleed nipple and the banjo bolt on the caliper, and they were fine.
This weekend, I noticed it doing it again, so I've looked very closely, and the stream seems to run down onto the front end of the caliper from - wait for this - the rear bolt holding the fender to the fork tube

So I'm thinking it has to be fork oil, not brake fluid, but surely fork oil couldn't be weeping out along that bolt thread, could it? The tapped hole must be nowhere near the innards of the fork tube.
So anybody any ideas???

Jim