Something could of happened to her (I really hope not). I hope though that if this is a "faux pas" that she makes it up to you and apologizes.. Your time should be as valuable as ours..

Happened to me once.  I cooled my heels in the hotel lobby for an hour.  Afterwards I sent her two emails saying I wasn't pissed (ok, maybe I was a bit), but I just wanted to know that she was ok and maybe we could reschedule next time she was in town.  No response.  She is O.C. based, but still in business, and still getting grand reviews, so that left a sour taste.  I thought about writing a bad review, but then it felt a bit childish on my part.  I put it in the "shit happens" folder.

Recently happened to me too

Waited almost 2 hours, really pissed me off.  She emailed later saying she never got the text messages and voice mails i sent while I was waiting.  Promised to make it up to me but was not readily available to reschedule. I will wait and see but if she honors her promise.  If not, I will spread the word.

One out of 25 isn't to bad.  If you want wait 24hrs and contact her again to see if she's ok. If she says she'll make it up to you, then you can decide what you want to do. You cannot write a review of a NCNS.  
As I mentioned, I simply move on, I rarely give an escort a chance to make it up