Haunting Question About A Rule

[SU DOG]

I'm not a big NFL guy, but having watched the end of the Saints Game last night, this question is driving me crazy to find an answer. Hopefully sudog03 or FUB, or some other guru of the game here will answer for me. There are 6 seconds left when Drew Brees connects with Ted Ginn for a 9 yard completion. Ginn is on the ground, and of course, in the NFL he isn't down until defensive contact is made. Texans CB Aaron Colvin immediately touches him and the play is over with 2 seconds left on the game clock, and a TO is called. A FG is then kicked and the Saints win. Why couldn't Colvin have hesitated for 2 seconds to expire before the play was over? I did not hear the announcers mention that possibility, and I'm probably overlooking something, but someone please explain the rule in that scenario.

[sudog03]

When a player goes down voluntarily (I.E. QB slide) the ball is automatically dead. You see NFL guys still touch QB's when they do that, but they don't have to. Same would apply here.

[SU DOG]

THANKS 03 that makes sense, figured you might know.