I noticed that the flap brace flanges did not match well to the bottom inboard main skins at the inboard end. It's because this end of the flap brace steps up onto two doublers, so that the flange actually gets a little twisted. I tweaked them with the seaming pliers.

Here, I've clecoed the two flap braces back-to-back so you can see the gap created by my flange tweaking.