Possible clawback question. I took an offer ($150 statement credit + 20000 miles) to upgrade from Amex Delta Gold to Amex Delta Platinum 2 months after paying Gold Fee. Now that Delta Platinum fees have increased, I will not be renewing when fee comes up. Probably will downgrade to Delta Gold. Will be only 10 months from upgrade offer. Any chance Amex will clawback, even though they changed terms of card after I upgraded?