I believe he was threatened in some way. The Chicago Way is to find the weak spot and bore right into it with thinly-veiled threats.
The only other logical answer is that Rahm took Kyl aside and told him the session had been taped and either Kyl recants or that part of the tape will be released.
I firmly believe that the paranoid Oval Office is wired for all meetings and that the fly on Obama's lip is actually a bug.
Leni
I would probably think he got threatened.
Does anybody here believe that the President is allowed to go into a room with one other person and not be monitored and recorded by Secret Service, video and audio? I seriously doubt it.