Bushwacker build, fuselage width, top and bottom differ on plan, error?

[LundiThembi]

Please let me know if I'm wrong about this. I built a second fuselage and it wasn't coming out square, same as my first build. I glued the sides to the bottom but then when gluing the top I couldn't keep it square. I measured the plans are realised the difference seen in the photo, the bottom is 7/16 of an inch wider than the top. trying to force fit makes the sides bulge!

Please let me know if it's me!