I just taped off the upper weep holes, and ran some pretty strong water at the window for quite a while. No leaking from the top as I originally saw. I'm still going to present it to the dealer, but I am confident at this point that it is the rubber caps not doing their job effectively.
Without a doubt, I appreciate the insight shared here.
On a side note and not at all related to the issue I noted originally, I need to find someone that has a 27DBS, so I can compare the slide window tracks in theirs versus those in mine. One of my slide windows has a track at the bottom that does not have the slits in it to take advantage of the weep holes. The rest of my slide windows do have them on the bottom. Not sure if this was done on purpose, but hoping to validate somehow.
//Edit: Just to clarify, I taped off the outside of the weep hole. So any other leaking should have been able to flow freely.