I could be wrong, but I don't remember Cargo turning down the Rockies on a contract extension. This contract was reached right after the 2010 season - the year Cargo nearly won the NL Triple Crown: https://www.mlbtraderumors.com/2011/01/rockies-agree-to-extend-carlos-gonzalez.html

So in terms of striking while the iron was hot, I would say Cargo did okay for himself. Perhaps he's turned down an extension since this deal was struck, but I don't recall that happening. He and the Rockies have had contract extension talks over the past year or two, but reports are that the Rockies were reluctant to make any multi-year offers. That's looking more and more like the right move.