I would guess that it’s the trick of the enemy to make you feel like you should have sinned. But I don’t know your situation, you’ve given me limited info to read.
I think I can relate: I recall as a teenager, a cashier forgot to ring up three garments for me, she folded and bagged them (she was new and I had several garments). I wasn’t paying attention, and as I walked out I thought the bill was much lower. I walked out of the door with merchandise and no sensor went off, but I turned around after leaving and went to her. She was so happy I returned as she was new and would have been fired. She bagged three dress shirts for me that she folded and forgot to ring up. I walked out paying at least 35.00 more. When I told family members (adults) I was told could have gotten then for free that I should have kept going. It left me unsure. Bottom line, it was the right choice and I’m sure satan wouldn’t want me to do that again so feeling unsure will help that agenda. Sometimes it’s the teachings of those in our family that echo in our head when we try to make the right choice. I don’t think my family is evil, but they wanted me to be ahead and were tempted to say, it’s oaky when really it isn’t! As an adult with children I’ve learned to have confidence in being more virtuous and modeling that for my kids. Hopefully you can find confidence in doing the right thing.