If McCabe lied to Comey. you can bet your booties that Comey KNEW he was lying. Cuz Comey....like a good attorney...would only ask a question that he already knew the answer.
You know, that sounds about right. Comey knows McCabe leaked, so getting McCabe to lie about it means Comey has some deniability plus future leverage on McCabe if Comey needs it. Very Machiavellian.