Reminds me of a similar situation I encountered on the now thankfully defunct Jet America Airways. I was flying in a window seat over the wing of a flight from LGB/ORD. I happened to notice fuel....and what looked like a substantial amount....spewing out of the wing around the rivets. After watching for awhile, I thought I'd notify the FA. She didn't even look and said it must be "condensation". I assured her it wasn't and that it was continous.
About ten minutes later, the cockpit door opens and down the aisle saunters the First Officer, nodding to the pax and talking to a few as he makes his way to my row.
He said " Are you the one who reported the fuel leak?" When I said I was, he asked me to get up so he could look out the window. And he said " I guess you're right! I checked the fuel gauges before coming back here and we are right where we should be fuel-wise. Tell you what, pls keep an eye on the wing and have the FA notify me if it gets any worse".
So for the rest of the 3 1/2 hour flight, my eyes were glued to the wing....