I made that discovery as a third grader while holding a flash light in order to help the nurse check my friends throat. I had never been aware of this and was extremely confused. I tried to see it again and then lookedbforbthe same thing in my throat. It is a flap to close of passage to the wind pipe/lungs when consuming solids and liquids rather that a gas. If you have ever had food slide before you could make the choice of when to swallow/gulp, which is a very natural thing that most people don't need to think about. It's like breathing. Sometimes if you are moving quickly or perhaps running in a flight of stairs, you might hold tour breath for a few seconds with out realizing it until you slow down or stop. By then you most likely only noticed because your are breathing heavily. Now if you have ever experienced food or often times a pill ready to go but already on it's way down, you may have attempted to get it back up or Automatically sent it down fast before it couldbgey stuck. My mom used tell me(when sea weed would take my sushivbwforw I could even finish chewing, ice slipping or mac n cheese), that my food or medacinr be sometimes water was "going down the wrong way." this is in fact what the item of consumtion is at least 'trying' to do. An annoying pain that may stay in your throat andvsometomes chest if it is a pill that went down. If you have ever tried to eat something that fit in your mouth just fine but was to big to chew might me slow and uncomfortable while it goes down. The pain CEO
these sinerios is felt when that small flap attemps to catch the wrong thing and simply direct it down the correct pasage way. Why have you never been aware of it's existence? Because most people don't know it's there. If you can stand the feeling of stretching your down out and down as far as it will go, you may be able to see it quite well for a few seconds. It pretty mug moves the opposite way as your tongue. Attached to the same area but in order to be effective, it need to have mostly just reactive movements. Otherwis you would be concentrating on which way it needed to go everytime you consumed anything! If end up taking a look,you are going to be trying to locate a rather thick flap that may be pinkish or yellow along with the thin vanes. It will appear to be curved up forwards the roof of your mouth when you are looking( It goes down when it need to but keeps it's shape and simply wool be curved that other way). It might look to be about an in in height from what you will be able to see.
I started to feel the same flap a couple weeks ago. My throat has been dry lately too but no coughing. Why does my flap bother me now? And I thought I was the only one who noticed the flap... I'm glad other people do too .