lost sense of smell then regained it after general anesthetic

About 18 years ago I suffered from a constant blocked nose. It went on for about 12 months or more. I was told by several doctors that it was Rhinitis. I think I could have told them that myself! Their concern seemed to be no more than a shrug of their shoulders. Very disappointing. Anyway, I used to manage it by using an over the counter nasal spray (Vicks). I had to use it much too often. Eventually I lost my sense of smell.
About 12 years later I developed prostate cancer and had it removed - all good now. I underwent a general anesthetic for the operation. When I woke up I had regained my sense of smell. It lasted for about 10 days or so before it faded away again.
Several years later I had a hip replacement done. Again with a general anesthetic. Blow me down, upon waking, my sense of smell had returned. It lasted a similar 10 days or so before fading away.
Has anybody experienced this phenomena? Would love to know if any body can throw any light on it.
I mentioned it to my doctor who again seemed non plused by the story, shrugged her shoulders, shook her head and merely said "I really don't know".