What is wrong with me..?

This morning I was walking through the Mobil Station parking lot at the end of my street on my way to the train when I saw a dollar bill in the middle of the pavement. It was not near any cars or people, just lying there all alone..folded in thirds. I bent down to pick it up and immediately started looking around for the owner. One of the gas station employees was walking toward the building so I popped one of my ear-buds out and hurried in his direction with the dollar. "I just found this in the parking lot." I announced, handing him the crumpled bill. I didn't even wait for a reply but turned on my heel and jammed my bud back into my ear. I was already late as it was. I did, however, linger just long enough to see/hear the Mobil employee snicker at me with a rather disgusted look on his face. Why did he laugh at me and why did he look annoyed? Maybe he thought I was a goody-two-shoes ..whatever that means. I personally have no idea what possessed me to to turn in a one dollar bill. All I know is that I suddenly felt naked and exposed there in the bright morning sun in the middle of the parking lot. I felt like everyone in the vicinity could see me and see that I was picking up some money from the ground, and in that moment I couldn't bare to be the one who took something that didn't belong to them. So I passed the buck, and walked away feeling morally clean and sparkling fresh. Crazy as it is, I think I would have thought about that dollar all day if I had pocketed it myself. None of this is to say that I think picking up abandoned money on the ground is a bad thing.. I mean within reason of course. I guess I just chose to go with my gut in a split second and not argue with myself. Well.. except until now. Now I wonder why I thought I was so high and mighty. Sort of feel like a pharisee or something. Like I wanted everyone to see my good deed of turning in one dollar to the parking lot owner's employee. But the truth is, it wasn't like that. In that moment I was sure that I could not put it in my wallet, and I still feel like I made the right decision. I must be losing my mind. It was one dollar. One..dollar. I must be losing it for sure.