I was not avoiding the details. What happened was: I used my card for her shopping, and she paid me back in cash. She had a lot of $20, so it was $40 or $50 short.
She did have the receipt.
I did not say anything. Since even when I count money just once, I can be wrong. A bunch of paper notes does have to be counted multiple times to be accurate.
I know this makes people embarrased, so I won't say anything.