This is the second time the dealer has looked at my car for this issue, but now, after pulling down the headliner, they have determined that the leak is coming from a body seam. After their first attempt to fix the leak, I still had water collecting in the passenger foot well, found some in the trunk, and had the seatbelt indicator malfunction and the air bag light turned on. The dealer has not verified if the seatbelt and airbag errors are related, but I assume they are because it happened immediately after a rain storm. They have a plan to fix it - hope it works.