Yep, plus, it's forbidden to sell any codes purchased from the humblebundle. :-/
The redeemed codes are bound to your steam account but wonder what happens when you sell the remaining unclaimed ones to another steam account? Maybe they would ban your redeemed ones on your own account because they could figure out that you sold the other ones? That stopped me from giving those that i dont want/need for free
I don't think that happens, they don't really track it like that.
It's for a charitable cause, and they are relying on us to not break the rule, if you do... well, nothing they can do about it :-/