accused for stealing loonie from the tip box

So yesterday I went to the pizza place to buy a slice of pizza for lunch, I pay my pizza, the cashier gave me my change. I put the change in the tip box. I walk away and stared at the pizza sprinkler then this random white guy who was eating his pizza in store got up, asking me:
"Did you take the loonie from that box?"
"No, I didn't"
"There was a loonie in there, what are you going to do with that?"
"I just put a nickel in there"
Then the cashier comes in "Oh, I cleared the tip box before she came in"
"Oh.... that's.... embarassing... I'm sorry"
It was dead silent for a while.
"I heard people do that so you know..." talking to the cashier.
I was just sitting there waiting for my pizza to heat up. He apologized again when he went back to his seat, and then again when I left the place. All I said was it's alright everytime he apologized, there was just no point talking to this guy.
It was funny and shocking at the same time because I rarely get accused for anything, I wouldn't even know how or why they would accuse me. Yeah, I don't even know when's the last time I got accused...
In this situation it was more embarassing for me because I had to announce that I put a nickel in the empty tip box 0_o