Those are the sketches you created before. Closed sketches filled automatically. You can delete them by selecting the filling or the sketches, or from the groups menu.
I didn’t create any sketches before? Or are they the faces I extruded from, but theyr’e not included in the final solid shape? So, if that’s the case, they’d never have become apparent if I hadn’t have done the move transform. Do people typically just leave them there in place? Or move the shape, delete them then move back the shape as a matter of routine?