Atta - Alomari At Portland

From 9/11 Encyclopedia:

For strange reasons, only one day before the September 11th attack, Mohammad Atta decided to fly to Portland. 

This time not with his "buddy" Marwan al-Shehhi, but with Abdul Aziz Al-Omari.
This disturbing detail in the timeline includes another oddity, that the flight from Portland to Boston was delayed for 40 minutes on that morning. 
How could they know? And why did they need only 12 minutes from their hotel until they passed through airport security? 

From the timeline: Tuesday, September 11, 2001 5:33 am ATTA and AL-OMARI checked out of the Comfort Inn.
5:40 am The 2001 blue Nissan Altima rental car, bearing Massachusetts license 3335VI, entered Portland International Jetport Airport parking lot.

It was parked on the first floor directly across from the airport entrance. 
5:43 am ATTA and AL-OMARI checked in at US AIRWAYS counter. 
5:45 am ATTA and AL-OMARI passed through airport security. 
6:00 am ATTA and AL-OMARI departed on Colgan Air en route to Boston, Massachusetts.