JM, I have the same make, model and year. I bought mine new from a local dealer. Before they turned it over to me, they had removed and resealed the marker lights in the overhead. They explained to me that several 'C's arrive from the factory with screws around the marker lights that were over tightened with power screwdrivers at the factory, creating hair line cracks. Re-sealing before delivery was Standard Operating Procedure for them. The water doesn't necessarily show up inside next to where it came in from the outside.