yup. on the faces with squares, you need, in Sketchup, to select that face and hit Delete. and keep doing it until the face Disappears then press Crtl-Z. it's very easy to stack faces. that causes the squares aka CoPlanar faces. it is easy to correct tho, it's just sloppy modeling.

Airport security is a burden we must all shoulder. Do your part, and please grope yourself in advance.