Why We Should Always Be Nice

My husband and I were shopping for a new dishwasher. We wanted the trip to be painfully efficient.  Check out the model on the Internet, see it in the store, buy it and get in and out. So that is what we did. Took under 10 minutes to spend like $500. The salesperson was helpful and efficient too, and when he looked us up in the computer, he told us he thought we looked familiar. He then told us he used to live by us, when we lived in our old house. We asked him more but really had no recollection of him. We were polite, but not overly friendly, we were thinking about the kids we had to pick up on fields all over the place. When we got home, my daughter was on college break and I mentioned to her about this salesperson and did she remember him? Oh yes! She remembered him immediately. She told us he was their most faithful  (probably only) customer and would come by their stand everyday when he came home from work and would buy their rocks (the girls were 6, 7 and 8).  Sometimes even pay. 50 when the price was .25 per rock.  I went back into the store the next day to kind of try to be nicer and thank him too.  He wasn't working and they would not give me any personal information on his work schedule, or even his last name.  I went in again 2 days later, still not there, and an associate told me they think he moved out of state....
  I missed my chance to be nice back.