Sorry, it wasn’t the debt limit, but the direction our spending has been going–up, and still going up, though at a slower rate–that was the issue in the credit rating downgrade:
Though the bill removes the threat of imminent default by raising the national debt limit enough to last until 2013, its cuts are only about half the $4 trillion in savings that ratings agencies Standard & Poor’s and Moody’s have said would be enough to confirm the country’s triple-A rating with a stable outlook.