I just did the opposite last night...took my iPad Mini in to swap it for an iPad 4. I purchased the Mini online with my credit card. When I went in store to return, I had already pre-reserved an iPad 4 and paid for it with my CC online, so I didn't need a credit card at all.
They asked if I wanted an Apple giftcard or if I wanted it to go back on my card (after they scanned the barcode on the Mini). I told them credit card, and she selected that on the iPhone/payment device, and I just had to sign my name.