Actually, I think that the face I was talking about just had its normals reversed. A face's "normal" is like the "direction" the face is facing. Pretty confusing, I know. But in Maya, toggling on "Polygon Normals" will show a ray shooting out of the center of each polygon, either from the outside of the face or the inside. For Pep, all normals should face outside, because it let's Pep know which side to put the tabs on. However, I think that, not only was the normal reversed (which can be easily fixed, although I don't know if Metaseq 248 has much normal support), but it's edges were not merged with its surrounding polygons, resulting in the red lines surrounding the face. Pep won't put any tabs around that face because it thinks that the face's edges aren't actually attatched to the surrounding polygons. That too can be easily fixed.
And still, the best way to learn 3D is not by editting the work of others, it is to begin your own model, and learn what kinds of objects suite you best. That gives you a chance to learn much more because of the longer modeling process.
