Is it from the small weep hole on the bottom of the clutch housing? Did you have oil spatter on the left side of your rear rim?
If so, gear oil is the likely culprit. I had some oil inside the belt case and as described above due to overfilling the final drive oil. You turn the rear wheel in its forward direction to help drain the oil, but you DO NOT turn it as you fill the oil. I did that and overfilled, which produced the oil weeping and spatter.
I changed the oil again and put in EXACTLY .32 liters of oil and the problem disappeared.
I talked to two mechanics trying to solve this and both said, "Honda's don't leak." So I concluded the problem was operator error.
Also, taking off the covers for this oil change is a good idea because you can be very precise about filling the oil.