Correct on both counts, it’s unlikely AmEx will notice and calling (for what reason) doesn’t make sense (and has significant downside risk with little or no upside potential).

It’s well documented that all Customer Service representatives are ill equipped to deal with infrequent unique situations, a call is unlikely to be positively productive in any way. Considering all the hassles they put us through in trying to deal with the rules as they state them, and how they sometimes change the rules in the middle of the period, we don’t have any moral or ethical obligation to alert them to an error in our favor. And it’s unlike returning “too much $$ change”, one specific individual is not liable.

I do suggest meeting the $15k within the appropriate timeframe to eliminate the remote possibility AmEx will notice.