A longer version of the event is available here.
The Pentagon's statement according to KTIV in Nebraska said Hagel meant:
Absolutely no slight toward any individual in the audience was intended. That's the last thing the Secretary would do under any circumstance, in this or any other setting. He didn't know who would be called next to pose a question.
The professor, Dr. Robin Gandhi said in a statement:
I was honored to attend Secretary of Defense Hagel's speech on Wednesday. I was able to ask a question and thoroughly enjoyed his answer. Before I rose to ask a question, there was apparently some confusion that did not involve me.