This week, Steam rolled out a change to its game-trading policy that prevents users from immediately trading video games that had been purchased as gifts, according to a report on Eurogamer.
From Steam's official forums:
"All new games purchased as a gift and placed in the purchaser's inventory will be untradable for 30 days. The gift may still be gifted at any time. The only change is to trading. We've made this change to make trading gifts a better experience for those receiving the gifts. We're hoping this lowers the number of people who trade for a game only to have the game revoked later due to issues with the purchaser's payment method."
Under the previous setup, a game could be bought and instantly traded to another Steam user, who could then find their access denied if payment from the original buyer was denied. In some cases, resellers have snatched up Steam keys to games with spurious payment methods then promptly resold them to others. The end purchaser in turn finds their access to the game withdrawn when Valve cannot process the initial payment.