Strange Things Are Happening

[Tortuga]

2006 1600 Nomad- Performed some maintenance, including fuel filter change, oil/filter change, installed new to me gas gauge, etc. While tank was off, removed radiator cap and saw that it was full. Checked reservoir and it was a bit above the "Cold" mark. I did nothing with regards to the coolant except check the level. Buttoned everything back up and went out to run some errands. When I came out of a store, there was a puddle under the bike. No smell, but a bit slippery. When it dried on my fingers they were a bit sticky. I drove home (6 miles) and took the side cover off. The reservoir was empty. I filled it a bit above the "Full" mark. Went out a few hours later and started it and let it idle about 20 minutes. Went out to check and the fan was going and there was a puddle. From the slope of my garage floor I could tell it came from the drain hose on the reservoir and the reservoir was full to the top and hot to the touch. What's going on?