Hi all --
I have my 90th anniversary 2013 R1200RT sitting in the garage on a battery tender and lightly covered with a cotton fitted bed sheet... much like I have done each horrible winter with all my previous bikes. It has around 1,500 miles on it and had its first service at 600. It's on the center stand and a piece of wood holds up the front fork so neither tire is on the ground all winter.
I noticed a leak on the floor of my garage directly under the front caliper one day so I placed a piece of white paper under it so the next time I could tell what the color of the fluid is. I have included some (rather poor) pictures here plus a stock photo with an arrow pointing to where the drip happens from. The big spot is about 5" in diameter and clear in color with a little blue/green on the edges. I touched the paper to the caliper to generate the smaller drip just to verify the fluid color.
I went through the bike with a flashlight carefully and cannot see any fluids coming from the fork seal or anywhere higher-up dripping down onto the caliper so I fear it must be coming from the caliper itself. I checked the reservoir and it appears completely full. I also squeezed the brakes and found no leaking. I felt all around the caliper and lines but my fingers came back dry... it's as if the drip is coming from inside the caliper itself somehow. I might be crazy but the leak appears to happen after a really cold snap, for example it was perfectly dry until the temperature dropped to 5F.