I received the same today. How is loyalty measured? I've only had a Velocity Escape card for a few months.
Except for paying for Virgin flights and the odd statement credit promo, I use my NAB Velocity Premium card when I can by by Amex, since it gives me 1.5 points per dollar. My son has an additional card on my account though, and he puts a few dollars through it.
So today I can see the points that were credited as per the usual statement cycle, but there's also another entry giving me 15% on top of those ("2014 November Amex Escape Card 15% Bonus"). This seems at odds with the postcard, which clearly states that the bonus applies only to purchases made between the 1st and 30th of November. Maybe there's still another 15% bonus to come?