I built my own wings and when I first fitted them up to the fuselage for initial rigging, I was off centreline by a maximum of 1/8" on the front spar on each side. TJ is right, until you get the #1 rib installed, the spars flex. I wasn't over worried about it. The #1 rib was installed after I drilled off the wing/fuse attachment (and that's even when clamping #1 rib per the manual) and I'm still off centre by about 1/8". Not concerned. Final rigging for sweep, dihedral and twist is bang on, although I've put a tad more twist than the recommended manual 1 degree.