"Smoking inhibits and ultimately destroys cilia, after which coughing is the only means of preventing mucus from accumulating in the lungs. For this reason, smokers with respiratory congestion should avoid medications that inhibit the cough reflex." (Human AP, Marieb)
Therefore, I suspect your throat clearing is a protective measure as a result of your paralyzed cilia.
http://groups.msn.com/FreedomFromTobaccoQuitSmokingNow/
favoritestrings.msnw?action=get_message&mview=0&
amp;ID_Message=79370
has a good explanation. Generally, cilia can regrow within 1-9 months.