Datapoint and inquiry: Out of the blue, my Citi Double Cash and TY Preferred cards were closed by the issuer. Have had each for 10+ years. Relatively light MS usage of DC card up until several months ago. FICO score +790. Telephone CSR couldn't provide any additional information (other than saying that it looked "strange"), letter to be received by mail apparently only says to direct written question to "ERU" at Sioux Falls POB.

Any ideas?