Predated: Would it not then be a second hand sale from the trademe seller? in which case its up to the buyer to make sure the goods are up to standard?
I'm just asking as I'm looking to put a house load of stuff on trade-me for my parents and it would be nice to know that if we sell a vacuum cleaner on there and the buyer comes back we can just go "not my problem take it up with Smith City they are the real retailer"
It's a grey area really, and depends on your attitude vs interpretation of the law. If you sold the items in good faith and in working conditions and they developed a fault that was covered under the provisions of the CGA, you would probably be within your rights to send the buyer along to the retailer to make a claim. Tho you may decide to refund the buyer and make the claim yourself.
If the fault was existing when your sold the item (especially if you knew it), you may have obligations under the sale of goods act, but then again, the buyer could quite easily make a CGA claim themselves as the OP could have.
Don't really want to take this thread off topic, but this is a grey area mostly because there hasn't been much in the way of legal precedent.