"The phone records don't include the substance of the calls they're just a written tally of who called whom and how long the calls lasted." (Source: NPR)
Perhaps, however if the Justice dept was concerned about a leak, it may have been tapping as mentioned in this transcript.
“DN: No, I absolutely do not, especially after this wiretapping incident, essentially, of the House of Representative. I dont think people are focusing on the right thing when they talk about going after the AP reporters. The big problem that I see is that they actually tapped right where Im sitting right now, the Cloak Room.”