I suspect Labour have been sitting on the original comments in the Rodney Times for quite a while, but the combination of recent bad news, National's poll lead provoked them to try to land a couple of blows on Key. George Galloway's recent ramblings (2) , which prompted Key's claim that "we've made it quite clear we won't be going to Iraq, we wouldn't have sent troops to Iraq" (3), presented them with the opportunity to launch their assault.
If this was something that Labour had been keeping in reserve, probably to trot out in the election campaign, then it is very suggestive of Labour finally realising that it is behind in the polls and it will be a long, tough battle to turn them around. Key is not Brash - Labour can't rely on him to slowly, grusomely fall apart. He's looking good to be running the country after the election. Which begs the question, how much more have Labour got on him? Hopefully, a bit more than this and Key's involvement with the Exclusive Brethern fiasco. That won't win Labour another election. But it is good to see they've finally realised they have to win it, rather than hanging about waiting for National to lose it.
1 - "Labour catches Key off guard," unattributed One News article, 7th of August, 2007. (http://tvnz.co.nz/view/page/411749/1279555)
2 - "Key clear over Iraq," unatttributed One News article, 29th of August, 2007. (http://tvnz.co.nz/view/page/488120/1258364)
3 - ibid.