There's a Sports Illustrated picture from the late 80s of Cade McNown actually puking in the UCLA huddle. Hard to tell if really sick or just too much gatorade; the elimination of which actually feels better.
But either way, I don't believe this for a second. The camera was on McNabb virtually the entire 4th quarter and he looked as normal as he did any other time. Remember that incident they showed on the bench with TO telling him something.
Perhaps the resolution on your set wasn't up to snuff, but he wsa not only breathing hard, he was wobbbling both on the way back to the huddle, and more prominently in the huddle. I figured he was really exhausted, as lots of the other players were fighting to catch their breath, especially after that last TD.