What happened to the woman’s flight?

M:   I thought your flight would arrive two hours ago.   What took so long?
W:   Didn’t they announce that our flight was delayed?
M:  I didn’t hear anything about a delay.   I thought everything was running on time.   What happened?
W:   We got on the plane on time but then we were held  up for almost two hours due to an unknown problem.
M:  That’s too bad.   Have you had anything to eat?
W:  I managed to get a sandwich on the plane.   How about you?
M:   I’ve had nothing but a cup of coffee.   I’m starving.   Let’s get out of here and find a restaurant.