Grease seal movement (?)

[les45]

My previous post was a bit wordy and didn't really ask this question. Has anyone had a grease seal move in to where it bottomed out on the bearing race. I recently changed a leaking seal and found it had pushed in about a quarter inch from the end of the hub. I am at a loss as to how this can happen and I've never seen it before. There is nothing that would cause a force on the seal itself to make it move. The bearing is seated against the raised shoulder that the seal fits over and the castle nut eliminates any lateral movement when properly adjusted. The only connection between the seal and spindle is the lip of the seal. I can't find any reference to this problem online but I did find a pic of one that had inexplicably backed out about 1/8". The seal that moved was one of the older metal type with a single, un-reinforced sealing lip. I replaced it (both wheels) with a rubber coated seal with spring loaded double lips.