No, he didn't:
Brian Rogers, a spokesman for the McCain campaign, responded: “In a press conference today, John McCain misspoke and immediately corrected himself by stating that Iran is in fact supporting radical Islamic extremists in Iraq, not Al Qaeda — as is reflected in the transcript. The reality is that the American people have deep concerns about the Democratic candidates’ judgment and readiness on matters of national security, and that’s why the D.N.C. launched their attack today.” [emphasis added]
Correcting yourself is what happens when you realize and correct your own error. Not when Joe Lieberman whispers in your ear. Plus as Josh Marshall notes, he's done it more than once.