Thanks people.
Yes, his question wasn't weird, I agree. But the whole tension afterwards from his side is what made this whole situation weird/awkward. He made me feel guilty in a way, and at our retail store we were taught to cause minimal guilt to the customers. For instance when a customer passes through a buzzer and it buzzes, instead of telling "Hey, you stole something" for example, we tell them "Hey, it seems something you carry causes the buzzer to buzz so we need to check out if there are still armed items left (we disarm them by sticking a sticker on the buzzer barcode sticker).