Mrstarker: Nah, taking a gift back seems like an asshole thing to do.
I bought a dozen copies of Deus Ex and am giving the away all around. If I send a code and the receiver doesn't redeem it, I probably will send it to someone else. Not because I am annoyed for not redeeming it, but because I have no way to track which codes I have already sent. If I want to give one away, I go to my gifts section and pick an unredeemed one. If I had sent it to someone else and they didn't redeem it, tough luck to them.
Same, although to a lesser extent (as I have less codes), with other games.