Kind of hard to see since I change my oil frequently and it never gets too dark but I've noticed this before.
Yesterday I just polished this area clean so I could tell if anything got on there.
On the ride in, I noticed the same two lines. Likely an initial drop or two then the highways wind blows it along toward the rear.
Any idea what this fluid is and where it's leaking from?

 

Check the cap on the oil tank, it may be coming from there and running down the back/side of the tank.When it gets to the bottom the wind catches it. That's assuming nothing else is wet on the engine.

 

You may be slightly over filling it and it is coming from the tank as mentioned above.

 

What other fluids do you have in the bike besides oil?