Door Sills Retaining Water

I have an odd water leak going on. The passenger side rear door sill is retaining water. When enough water builds up, it leaks through the inner door seal and spills onto the floorboard. If I open the door after it rains, I'll get a gush of water off of the door sill.

I've taken the door apart, and there doesn't seem to be a way that water from the outside can migrate through and end up in the door sill area. Has anyone seen an issue like this? I wanted to ask around before I just started replacing seals.

Mine does this sometimes too and I have yet to investigate why.

I noticed this today on my RR door as well, no water inside the car. The LR was relatively dry.

I might just guinea pig this and replace the outer door seal and see what happens. As these cars age, perhaps the seals aren't quite sealing on all surfaces and allowing water to ingress. It looks as though any gap in the seal (especially on the B-pillar) would allow water in, which is then retained by the still-sealing-enough bottom part of the seal. Enough water gets in and voila, water on the floorboard.