One of my first models from several months ago, when I began with Blender, doesn't work with a mirror modifier properly. While tabbing between Edit and Object modes, the object origin remains in place, while the mesh location is different on the x-axis by a half a blender unit. In Edit Mode the mesh favors the right as in +5, while in Object Mode it is -1! I did try clearing scale, rotation and location. Any ideas?
Here is the blend file: http://www.pasteall.org/blend/33015