Not that I don't trust the advice given on FT, but personally I would have called HHonors to verify this offer. There are many warnings about e-mails "phishing" for personal data. This sure looks like one of these suspicious e-mails. Not saying it is.

www.hilton.com:

Information Regarding Internet Scams

Protect yourself from scams on the Internet that imitate legitimate companies in order to obtain your personal information.

The names of a number of major companies have been used in such scams and a recent phishing attempt was made fraudulently using the Hilton HHonors name to request personal information.

These scams, known as Spoof or Phishing attacks are not easy to spot, but do share certain characteristics. They may ask you to provide, update or confirm sensitive personal information. Here are some signs that should alert you to a possible spoof/phishing attack:

Sense of urgency – threats to close your account, fees charged, etc. if you don’t respond immediately
Obvious spelling errors – used to bypass spam blockers
Requests for inappropriate data such as bank account number, ATM PIN number, Social Security number, etc.

IF YOU RECEIVE AN E-MAIL PURPORTEDLY FROM US, WITH ANY OF THE ABOVE SIGNS, YOU SHOULD NOT RESPOND OR CLICK ON ANY LINKS CONTAINED IN THE EMAIL.