Hi Sam,
It seems nerves can do funny things. Gordon was told his ear lobe would be numb for the rest of his life after his radical neck dissection. Well, it was for awhile, and then the tingling started (actually the left jaw as well as the ear lobe). The surgeon has now revised his position and says Gordon will be in this "half-awake" state for about a year (or maybe two?) and then it will probably go away. All I can glean from this is that it's anybody's guess as to what the outcome will be, so don't give up on your lip returning to normal.
Anne