My guess is that it was connected to the video he recently released. The quick and, possibly, helter-skelter race to apologize/defend his bombing in Jordan caused them to slip up. Al Qaeda's more standard and quite secret procedures of getting a video public were violated. I'm sure that is a weak point in staying undetected and the normal methods are either responding to events by video after a considerable period of time or having the video pre-prepared/prepostioned such that the trail is cold.
Like I said, just a guess. Maybe the rumor is not true, anyway.
(Another hat tip to Instapundit. Follow this link for more links to more extensive coverage.)
More: GatewayPundit has lots more.
It is extremely interesting that Coalition and Iraqi Froces tried to invade the building after some four or more hours of trading fire. It was only at that point that the terrorists blew themselves up, in the process killing some of those rushing the building. Capture was obviously intended because otherwise the good guys would have just blown up the building. I can't thik of why they thought they would be successful.