Gripe of the gift

Recently i tried selling a couple of PS3 games i had completed and listed them on a forum. Among them was a game (Killzone 2) that Mabeline had bought for me sometime this year as a gift (i completely forgot it was a gift when i posted). Someone wanted to deal for the game but a day before we were supposed to meet, i happened to mention to Mabs that i was meeting someone who wanted to buy it. Her reaction was along the lines of 'huh? you're selling the game i bought you?' I then decided to cancel the deal and keep the game.

On my birthday, Mom and Brandon also got me a PS3 game (Ghostbusters) which i also completed and posted along with another game in the same forum. Just yesterday someone bought the game from me for $52 and when i saw Brandon today i gave him the cash.

His reaction was 'You sold my present?' I rationalized aloud that i had completed it and selling it was better than letting it collecting dust at home, to which his reply was you wouldn't sell a birthday present like you wouldn't sell a birthday card. I gave him the first answer that came to mind: It's different cause no one would want to buy mine(your) birthday card. But this incident got me thinking.

So it is wrong to sell a present? I never really had a firm stance on this, but i feel that if you give a gift to someone and then think its wrong for that person to give/sell/throw your gift away, can i suggest that in the first place, you have never actually fully given it away? Gifts (like Love) should not have Terms and Conditions attached to it. It's unconditional.

I can't expect everyone to understand or take my position on this, but i guess that will be how i treat any thing i give away from now on. Feel free to sell, throw, burn etc anything i give you. I don't mind. I shouldn't. It's all yours to do whatever you wish with it. Having said that i should also be more mindful and sensitive to dealing with gifts received.