Every athlete, especially right before, during and after a contest can be vastly different in your experience than seeing them later on. I am glad that many backstage are cool enough to let me take their pictures, while concentrating on the contest. At the Meet the Olympians Thursday evening, almost every single competitor was awesome, friendly and nice. Including the competitor you are taking about. She was even gracious backstage.
Backstage, their is a lot of emotion running, especially when one realizes that the callouts may not go there way. There is anger, resentment, and a myriad of other emotions, coupled with family members or friends also feeling various ways. These competitors train and diet very hard, and sometimes, even not placing where you want can be devestating.
I have seen it many times, people very upset, backstage, later on, and you feel for them.
Yes, many are cool to take their pictures afterwards, but some are just quite upset.
But don't let this one incident mess up the entire weekend. It was just a great weekend, seeing the top competitors around, being in Vegas in the best show. You can't beat it.