Hazel's Mind Bender

Can you figure it out?

One bright, sunny day, a cafe owner decided to hold a chess tournament. In order to promote some excitement, he chose a blitz (5-minute) time control. The tournament was fairly successful, with a number of players of different age and skill level. As the cafe owner made his way through the crowd, he noticed one player staring intensely at the board. The game had already begun, and the clock was ticking. Ten minutes later, he was still staring at the board, yet neither his flag nor his opponent's flag had fallen. Assuming the clocks were functioning properly (with no lags), and clocks were not stopped during a game, how is this possible?

Note: Also assume the game was won on time.

Answer: The player watching the game had already finished his round, having checkmated his opponent (or vice versa) before either flag fell. An eager chess enthusiast, he went over to watch his friend's game, which was still in progress. When the game ended, the player reviewed it with his friend, and thus, was still staring at the same board ten minutes later!

The cafe owner probably noticed because he wanted to start the next round :)