I hear TIMEOUT but dont know who called it

[lmeadski]

This was a JV game and I am the trail on a 2 man. I am right in front of the scorers table and we are under a minute. It is a tied game. From behind me, as time approaches 30 seconds, I hear the coach call time out (remember, I am facing the court, they are directly behind me). I blow my whistle to stop play, turn, and see it was the assistant coach who called the timeout. The head coach is giving him a look like "I didnt WANT a timeout." He looks at me and says, "it was my assistant. I didn't want a timeout." We did charge them a timeout in this situation. My question is this: should I have turned away from play to see who called for the timeout prior to blowing my whistle? I am afraid if I turn to see who is calling the timeout, I may miss something on the floor, plus, a few precious seconds will continue to tick off as I look between the two to determine who actually called the TO. What say you?