Whenever I go into Sub-object mode...like working with vertices, edges, etc, and I move or scale my selection, the vertices (or faces, whatever) will snap to the object behind it. No, my snap isn't on. It must be a bug. When I rotate the view so that there isn't a seperate object behind my selection, everthing moves fine.
Like Modron said, sounds like that some how you got your self in to Retopo mode for your mesh … Just turn it off in the Mesh panel in the Editing context (F9) in Edit Mode …