Thank You Card

After we got married, I received a nice present to celebrate from a friend of my mother-in-law. I've never met her, but she thinks of me. I immediately sent her a thank you card. A few days later, I got a thank you card from her for the thank you card I sent. My husband laughed at. If I send her a thank you card again, it definitely continue forever... thank you card for a thank you card for a thank you card for..... but it's nice of her.