Leakage from rain?

My wife and I are new to TM'ing and this forum. And yes, we have a roof leak.

We purchased our '03 3023 last year and took it out just 3 times before storing it in the garage for the winter. Each time out, we had measurable precipitation but no leaks during the first two trips. However, on the third trip out we were in a real downpour for over 2 hours and observed a steady stream (.25" wide) of water coming down the right side rear shell where the wall and roof meet. The water comes down and pools slightly just behind the stove and then drips down to the floor by the door. The leak would seem to be right where the front shell and rear shell overlap.

I did a quick inspection and did not see any gaps or obvious missing caulk before I put the TM away for the season, so I plan to do a careful check when I de-winterize, hopefully in March.