weird, I ask my (2 different) friends to buy them for me both times. I gave them 10%/25% off the price of the card value. Got 2x $50 both times.
From what I remember the last time it was 25%[+5% with red card] off, the last last time it was 10%[+5% with red card] off.
proof:
Aug 6th 10% off psn/xbl/eshop cards
http://forums.redflagdeals.com/target-10-off-all-gaming-cards-psn-xbl-eshop-1527289/
Sept 1st 25% off psn cash cards (pricing error, should have been 10% off) end of page 4, start of page 5 where people reporting they got 25% off PSN cash cards
http://forums.redflagdeals.com/target-psn-xbox-live-cards-25-also-10-off-currency-cards-1544931/
I think what's confusing you is Sept wasn't the last time they did a card offer. The last time was the offer a couple weeks ago where it was buy 1 get 1 20% off. Sept was the second last time.