Rear window wood, 30 Town sedan

[Terry, NJ]

OK, I can't get the hang of posting pics, so I'll have to give a good discription. Close your eyes and imagine the rear window of a T.S. and the wood that surrounds it. We won't concern ourselves with the top, but the bottom (Belt Rail?) and sides. The sides are two upright pieces about the height of the window (tenoned) + the "Riser" piece that goes directly over the "Belt rail" and the bottom of the window. It is this "Riser" that I'm working on. I made it the length of the original pc, (23 1/2") long, but fitted between the uprights, leaves about 1/4" gap at each end. Can this be correct? The two pcs match perfectly, but I can't believe they aren't supposed to fit snugly between the uprights. I'll remake the damn thing if that's what it calls for but I really don't want to.
T.I.A. Terry