I would not get too worried until you actually fit the wings.
The fuse rear spar will flex that much. Before you fit the wings, just make sure you bevel all sharp edges, to help the parts slide together. A little lube would not hurt. Make up some drift pins to help align the spars with the steel splice plates. This way you won't mess up your good bolts. Only use the correct bolts the very last time. The wings will come off/on several times. Have the bottom nut plates holes marked, and ready to drill. Have a couple helpers and take your time. Good luck.