Here's a tad more data for those attempting to confirm/disprove AA theories.
I have previously redeemed erewards for AA but also for Hilton (annually), Blockbuster, and don't recall what else. I never received a targetted email. I never noticed any offer about this promo on my erewards page, though I do not check it on a regular basis; it is not there now. I redeemed $25 for 500 AA miles last week. I have not gotten the offer since (though I hoped to).
I've been a member of erewards for more than seven years. I do not recall which sponsor I originally used.