Yes, that was back in 2001 when Greenspan was arguing for the virtues of President Bush's tax cuts. That concern turned out to be somewhat misplaced. However the inaccuracy of the projections being used at the time, which did show the country paying off its debt inside of a decade, should provide some caution in assessing long-range projections.
The inaccuracy of these projections might cause some to question the wisdom of the Washington Post's decision to headline a piece on President Obama's budget:
"Obama budget: National debt will be $1 trillion higher in a decade than forecast."
An assertion like this implies a level of accuracy in these long-range projections that is not at all justified by their track record. It also would have been helpful to point out that $1 trillion is a bit more than 4.0 percent of projected GDP for 2022.
While this article includes the criticisms of people who feel that President Obama did not go far enough in reducing the deficit in this budget, a balanced piece would have included the comments of some of the many economists who criticize the administration for failing to have sufficient stimulus to bring down the unemployment rate more quickly.