Swing arm bushings

Had to remove the swing arm to r/r the drive shaft boot . Put the arm back and now have a gap on the rigt side of the arm that shows the threads of the nut.had out 3 times to check the seals and bearings and all good . Torque all by specs (wasn;t like this when took down) no play no where and nothing in a bind. Think frame sprung ? Had new bearing a year a go