Sure, be emotional about the situation and the mistake, but channel that emotion into competitive effort instead of into crying about. Cry afterwards if you feel it's necessary, but crying mid-workout is of no benefit and probably even detracted from her performance. She recovered incredibly well (4 reps behind #1 Cheryl Brost in that heat, if I recall), but she probably could have done better had she not cried.
That's what I mean in this case by athletic discipline; the ability to channel the emotion in the right direction. Clearly she is disciplined about her training. She made it to the Games and placed well, after all.
(wfs) is what you do in that situation; not cry. Pick yourself up and haul azz.