JetBlue TrueBlue - Email offer for 50 points for a new Amex card, but am I eligible?

I just received an email offer for 50 points for first use of a new JetBlue Amex card. The fine print says new members only, and each person only gets one signup bonus. That would officially disqualify me, since I got that bonus about 2 years ago. I cancelled my JetBlue Amex early this year.

Does anyone here know whether Amex enforces this one-time-only policy on the signup bonus? I recall once Diners Club turned me down because I had held their card EIGHT YEARS earlier.

I believe if you sign up for another card, you'll only get the difference between the current offer and the offer you received with your first card. So, if your previous card came with a 25 point bonus, by signing up with the card again, you should get another 25 point bonus.

I seem to remember hearing/reading this somewhere, but I don't know what the official policy is on this - so if anyone can find a source, or has some personal experience on the subject, that would be awesome!