Actually, what's happened was this. You can receive 5% off Disney Gift cards (and most other merchandise) when purchased with a Target Red card (either debit or credit). Some people found there was a glitch in the system at Target.com and they were able to have their account there have the default payment as their Target Red card (so the system would give them the 5% off any purchases), but when they actually checked out, they used Target gift cards they got at a discount from another site.
Target finally caught on and now, when purchasing Disney Gift Cards, you can only get the 5% off if you actually purchase with the Target Red card.