Confirm your mobile number with Tesco

Received a letter today from Tesco - "we need to confirm your mobile phone number - we recently tried to contact you about your account. However, the message couldn`t be delivered because it appears we don`t have a correct mobile phone number on file for you"
Logged on, as suggested, to update my contact details and "lo and behold" they are correct!
Has anyone else experienced this and should I "update" my details by just re-entering the same details.
Is this just another "mistake", like those I have had from various banks such as messages asking me "to go paperless" when I have always been paperless, and also telling me that I need to implement certain criteria to earn interest on current accounts when in fact I already have everything in place!