Misunderestimation...?

In today's society we do many things which we don't even think about.  We hold doors for people behind us, cover our mouths when we sneeze, and even wipe our arse on a semi-regular basis.  We even say "please" and "thank you".

However, yesterday, I realized something.  I was getting my sandwich (I love sandwiches) and when the man was done with it, I said, "Thank you" and he said, "You're Welcome".  Well, that seems fine, but I wasn't finished for some reason.

After he said, "You're Welcome", I said, "I know."  I really didn't mean to say it, it just came out.  I sort of stared at him in amazement as to what I just said.  Without realizing it I, subconsciously, acknowledged the oddity of his statement.  A statement which everyone, even myself, says.  

Thinking about if for a while made me question the phrase even more.  The phrase is an acknowledgement of me being thankful and that I without obligation for the favor or courtesy received from the person.  

Without thinking about it, I responded to the statement, which people don't typically respond to.  What does saying, "I know" mean in this situation?  It means A. The person thinks I'm a jerk and B. I know that I am thankful (I said thank you, didn't I??) and I know that I have no obligations to the person for anything.  EVER.

From now on, instead of saying "thank you", I'm going to say something that they need to say "thank you" to.  For example, if I say "I appreciate what you've done for me", I would be stared at rather strangely, but they would have to say "thank you."  Then, I can reverse the roles, and I can say "You're welcome."  

I can see this not catching on...at all...but I will certainly enjoy it.

Bye for now.

-Nick