Me too. My 2011 Ridgeline had a horrible leak all along the front headliner from a poorly installed windshield. It took 1 1/2 years for the leak to show. The new installer mentioned that the leaking windshield was not quite right. Slightly different shape and it creaked. This one is tight and silent!My knee jerk answer is windshield. I have seen it more than a few times. A poor quality windshield replacement, the technician does not adequately prime the pinch weld and rust forms. The rust then separates the urethane from the pinchweld.
Its interesting their test showed no leak. I am willing to bet on my diagnosis.
Do you have a sunroof ?