I understand the fun that Teresa and her postman had. It was an innocent and not a hurtful remark but one which can only be used between people who already know one another and in certain circumstances. As the old joke states IT IS NOT WHAT YOU SAY BUT HOW YOU SAY IT.
Teresa and her postman have a good relationship which involves taking little "digs" at one another but no harm is done and no harm is intended.
With different people in different circumstances it would not work.
Keep on trucking Teresa. You are a very positive advertisement for our community.