I think that's fine. The ground is a plus. The important thing is to ensure the same potential for the airframe, fuel/jug, and funnel. The fuel is picking up a static charge as it falls through the air. If it builds enough, it will discharge. Tie all the components together and it can't build.
Personal experience.
I was draining the tank on a Piper Cherokee, had a 5 gallon can set on top of a plastic milk crate with a large, metal, funnel in the can. The fuel drain petcock was open and a full stream of gas was flowing into the funnel.
After a few minutes, I approached the airplane to shut the fuel off and remove the can. When I bent over and touched the wing, I heard a slight snap, look down
and saw a perfect blue flame flowing up the sides of the funnel, a full stream of gas was still flowing into the funnel.
What to do? I didn't dare to touch anything in fear of causing the flame to ignite the fuel as the flame was getting larger and proceeding up the sides of the funnel.
I took a huge breath, bent over and blew the flame out! sat down on the floor, my knees were shaking so bad, I could not stand up.
In retrospect, GROUND EVERYTHING. as Dan suggest, I still get cold chills thinking about this, happened 20 years ago.
DIck