I was separating the two parts after paddling the way I always do (i.e. open lock, and pull apart while rotating a bit back and forth) and noticed that the joiner was rotating on the paddle shaft it's supposed to be bonded to. After pulling the other paddle out I noticed that I could easily rotate it by hand and once I got home it took no effort to slide it off. The joiner is smooth inside and the paddle shaft has what seem to be blobs of glue.
My suspicion is that it needs some fresh hot glue. I have a temperature controlled hot air station, so it shouldn't be too difficult. I don't know how hot I can make the composite, though, and the orientation is also a bit tricky.
I did contact Michele, from whom I bought the paddle, and she forwarded to Gara. I was hoping to find a quicker answer here...