Did I in fact break any laws if I didn't hide any product and I never got closer than 50-100 feet from the exit?

I was shopping at a store using the self-scan aisle and I scan 1 item and pay for that one with other items in the cart which have not been paid for and not bagged because the item I paid for was for someone else who was paying cash and wanted change from the item. I was paying for all the other items. I paid with the cash to get a receipt and change. The other items that haven’t been paid for or bagged are still there not paid for. There wasn't much in the cart. I needed cigarettes and I’m paying with a debit card. Cigarettes are kept at customer service and I grabbed the wrong size of cat food so I needed to exchange sizes. I was going to ask for the cigarettes and pay for the remaining items to keep it on one transaction. I walk towards the customer service man who was also in charge of u-scan. I took two steps and the off duty police who is working security asked to see my receipt which I showed him and told him I’m not finished yet. That I needed a different bag of food. I went, changed the bag of food and bought my cigarettes and pop. On my way out, the police man stopped me and started chastising me for doing what I did. I tried to explain what I was trying to do but he kept interrupting me saying that somehow we aren't understanding each other. He said that if I paid for an item and have others that aren't paid for and exit the lane that it is theft and he could arrest me for theft. I calmly tried to explain what I was doing and he basically told me to shut up. All this with people watching. Keep in mind that this is my neighborhood grocery so there are people I know. I told him I was unaware that was breaking the law which is true. I had never heard anything like that before. I have done similar things at the same store before and no one ever said a word. I apologized for doing it and said it would never happen again and he finally let me go.