amok: Yes, I would at least put it on hold until HB have clarified the issue. I have just dropped them an email about it. This seems very suspicious, if Tremor is reselling HB keys, then it is a clear breach of contracts, and the keys are illegal. This is beyond gifting spare games.
SirEyeball: Well I am at a loss here should I call of the GA and be left with unusable keys by anyone as I actually also bought the bundle so I have the keys myself? that seems wrong somehow.
I would at least frozen the giveaway it until HB has investigated... Giving away illegal keys also seems somehow wrong (if they are illegal, that is)
Waiting a bit will let you know whether these keys are good or not, if they are good - then go ahead, but if they are not - contact Tremor and get a refund.