Free Custard at Andy’s

I took my son for a first day of school treat today at Andy's. As soon as the cashier handed me back my credit card, she handed me a white bag and said, "Here, this is for you. It's a promotion we're doing." I was surprised and could tell there were take home containers inside. I made sure to thank her and set the bag aside so I could grab our order. Once we got home I opened the bag to discover a quart and a pint. I'm fairly sure it wasn't a promotion. I'm wondering if maybe it was an order that wasn't picked up.

This was very good fortune indeed and I'm curious to see what you guys think could have been the reason. Thanks!