Has this happened to you when you go shopping with kids/babies?

So I went to walmart got a few items it was time to pay. Well my son had woken up he was on his car seat inside the shopping cart I got his blanket to cover him so he would go back to sleep. My mother in law and I put all items to pay. Once we got to the car as we were loading things to the car there was a baby lotion that we didn’t pay for and didn’t see since it was covered by baby’s blanket. I feel bad because I did end up leaving although it was never my intention to leave or steal whatsoever it was an accident. And with babies or toddlers things come up in the shopping cart without noticing. Idk wether to just keep it or go back tomorrow and let them know i wasn’t charged for this? It was an accident. Has this happened to you? Or What would you do?