Let's see what Sen. Chuck Schumer (D-NY) says about this.

Sen. Schumer has said that McNulty told him in a private conversation that Kyle Sampson and other aides, like Monica Goodling, were to blame for his incomplete testimony. According to Schumer, McNulty told him, "I was not told that these things were happening by the people who were supposed to brief me." McNulty had asked direct questions, Schumer said, and Goodling and Sampson had stayed mum about the White House involvement in the firings.

But today, McNulty testified that he hadn't "accused anybody of withholding information." He'd simply acknowledged in the conversation that he hadn't had that information when he testified -- "that was basically the extent of it." So just one big misunderstanding.