I had my Citi mastercard replaced in Nov same reason, a mechants systems was compromised and they were issuing new cards as a preventative measure. Major hassle for me changing everything, especially during a time I was travelling.

My biggest complaint, Citi would not tell me which merchant it was so I could quit giving them business. Thought about cancelling the card but didn't try playing that hand. I think they should be obliged to communicate toi us who can't protect their card data.