Well I feel like a knuckle head!
I started working on ours a little and our has the one peice interrior end cap as well. I never noticed it. It must have been the disgusts of the baby blue paint over it that I could not look at the ceiling for more then a few seconds at a time before I had to avert my eyes! I hate baby blue and it looks particularly bad with the wood cabinets. I suddenly relaized there were no seam past the first rib. I forced myself to look closer, despite the color, and sure enough it's one peice.