This statement was made on Monday, in a letter to Paul Rand:
"Holder said it was possible, "I suppose," to imagine an "extraordinary circumstance in which it would be necessary and appropriate" under U.S. law for the president to authorize the military to "use lethal force" within the United States."
Then on Wednesday one of the Senators asked for a clarification:
" In testimony Wednesday before the Senate Judiciary Committee, Sen. Ted Cruz, R-Texas, pressed Holder whether he believed it would be constitutional to target an American terror suspect "sitting at a cafe" if the suspect didn't pose an imminent threat."
To that, Holder responded "no".
I don't think the "sitting at a cafe" and "didn't pose an imminent threat" specifications were part of the original questioning that prompted Holder's quote from Monday.
Now, if the "not engaged in combat" was part of the question from the start, the only reason I can think of for a delay would be if they needed to have some discussion on what exactly "in combat" would mean in the context of a terrorist in the U.S.