The red stops at the trailing edge of the spar, the white is open bay. It did the same thing as noted with your pic, the red shrunk up tighter than the white. I used the trim iron on the white until it shrunk and matched the red. I have had this happen before on both solid backing and open bay's, I think it all depends on the color of covering as to the rate it shrinks. I did a profile several years ago, see pic, and it was like an old prune but the trim iron worked it all out.
On yours it look's as thought the blue is shrinking faster than the red, continue shrinking the red until it get's close and then do both together in small increments. Just because one is tight does not mean it can not be heated slightly more for the other to catch up.