In 7 eleven, an old man kept staring at me

I looked away and looked for the stuff i wanted to buy then i looked at him and he was still staring at me. I approached him and i asked him why he was looking at me and asked if he had a problem. He said, "you remind me of my daughter who passed away last year. I am so sorry if i was bothering you." I started feeling emotional and i told him how sorry i was for being rude to him. He told me that it was ok. He then said, "could you please do me a favor, go with me to the exit door and say goodbye pa. I just want to feel like im with her for the last time". I said yes and as i brought him to the exit, i said goodbye pa as he left bursting in tears. After that I got some chips and brought it to the counter. The cashier says, "that would be $2456 ma'm." I was surprised and i told her that there must have been a mistake. She said, "your father said that you would pay for everything". I tell her that hes not my dad and i dont even know that guy. The cashier tells me, " im not stupid, i just heard you say goodbye pa to him."