At the two minute warning before the half, Miami faced 2nd and 9 at the Washington 12. They held two timeouts.
Two plays later, it was first and goal at the two, but Miami had only 42 seconds left. So, those two plays took about a minute and a quarter.
Miami ran on 1st down, and took a long time to get to the line for the second down play. That meant they were down to 10 seconds when they snapped the ball to run it again. Since Chatman was stuffed on the play, Miami had a chance to call a timeout with 4 seconds left.
Sure, they scored on the 3rd down. But, what was Cam thinking? That he could keep the timeout for next week? Why not use it, and have better clock management skills.