Good catch - Yes, it is not fully attached. I did the same at the polyhedral. Mostly to see how it looked. I'll probably attach at the polyhedral on the next wing, but like how the root turned out with it floating.Looking very very nice!
I cant quite tell from the photo - is the covering film attached to the top of the rib at the polyhedral joint? Kinda looks like it was purposefully left unattached to provide a nice transition from inboard to outboard panel?