When SPG card changed from Platinum to Red/Silver it was considered a new product, but this change from Red/Silver to Purple is apparently not. Suggest you call and ask a CSR if you have had this card before and are eligible for another bonus.
My card was in 2012 which I'm pretty sure was Red/Silver. Not sure why the first switch was considered a new product and the second is not. The fees and benefits have all changed. I was thinking of taking a chance but CSR says I'm not eligible for the bonus as expected.