"Are you sure this is a real license?"

Today I went to Sater Bros. to get some floss. Yes, that's right, dental floss. I got to the check out line I whipped out my checkbook to write them a nifty little check for my minty fresh dental floss. Now, in order to have them accept my nice little check from my nice little checkbook they have to see my driver's license. I'm from Washington State so it would follow that I have a Washington State driver's license, which I do. It's quite lovely in fact, it even has my picture on it. The nice young man who was my checker looked at the license, then looked at me and asked, "Is this a real license?"
I replied with the obvious answer, "Yes."
"Are you sure?"
Puzzled I responded, "Yes."
"Why is it up and down instead of sideways?" he asked. I then explained to him that Washington has something called a 'graduated license' and all the gore details of that program (which would take far to long to explain here.) The young man persisted in looking puzzled and called his assistant manager who he probably hoped would rectify his puzzlement.
They conversed for a moment before the assistant manager looked at me and asked, "Are you sure this is a real license?"
"Yes." They proceeded to call the manager. I being highly amused at all of this stood there quietly wondering when they would figure it all out.
Soon the manager appeared. He took one look at my license and asked, "Does your license number have letters in it?"
I replied, "yes. It is preceded by the words, 'license number' at the top of the license in large blue letters."
"Are you sure this is a real license?"
"Yes."