The whole Joe Wilson - Valarie Plame episode was a joke. Joe Wilson was never officially sent to Africa by the CIA, he was never on their payroll, he never got orders, he never filed an official report. He was and is a complete fraud. His wife sent him there and he basically took a one week vacation, and came back to give an oral report to the CIA, which dismissed his report as completely worthless.
Then he proceeds to join the John Kerry campaign and puts out an op-ed about what he "didn't find" in Africa, and accused Bush of lying in the state of the union address. Once the media started asking questions about this "report" (the one that never existed) the White House was completely dumbfounded. Who the hell is this Joe Wilson? What "report" is he talking about? He doesn't work for the White House, and he doesn't work at all for the government anymore. They quickly find out he is a has-been former Ambassador (to Gabon) and that his wife works in the CIA. The media keeps snooping because they want to believe Wilson, they finally got a guy who can nail Bush right before the election, so they don't bother questioning his story, they just run with it. So Cheney and Libby find out about Plame and start asking the CIA what the **** is going on. The CIA explains that they indulged their resident bimbo, Plame, in letting her husband take a glorified vacation to Niger so he can talk with his old pals. It was never anything official, he was never paid, he never got official orders, he never filed a report. So the media meanwhile is bugging the shit out of the white house about who sent Wilson to Niger? It wasn't the White House, it wasn't the CIA, so who? Well the truth of the matter was his wife sent him, and that is exactly what the media found out - the truth. It wasn't anyone "outting" Plame. It was finding out Plame was responsible for this bullshit lie that Wilson made up.
Joe Wilson also claimed it wasn't his wife that sent him, which of course, as an outright lie. The Senate investigation report details that the only thing that was verified was that Plame did request to her superiors that her husband be allowed to go to Niger. They also found that Joe wilson never had access to, nor filed any official report about uranium in Africa.
So yea, I can't imagine why Cheney probably answered "I don't recall" concerning a report he never got, from a man he never sent to Africa. Keep in mind this was right before the election, I am sure Cheney wasn't spending too much time thinking about when and where he happened to mention Valarie Plame and Joe Wilson, two little people that he had nothing to do with, two little people that were lying on behalf of the John Kerry campaign in yet another liberal smear attempt of Bush.