Tried this yesterday on a $100 GC that is on sale for $90 at Safeway. Successfully loaded BB at Wal-Mart after getting the GC pin via a phone call. Now to find the $500 GCs or look through this long thread for hints or wait for FM/MMS to do the grunt work!
I thought that I recently read that some CCs no longer offer 5 percent cashback on GCs purchased at grocery stores/drug stores/department stores/electronics stores/wherever else they usually offer 5 percent back on other non-GC purchases. Hopefully the Amex Preferred 6 percent (capped) at grocery stores is not one of those.
Seems like Safeway did not give gas rewards on the GC purchase.