Am I the only one who doesn't really care? There's a time and a place to ask for autographs, standing outside someone's car at an airport while they're heading to a flight and being swarmed by paparazzi is NOT one of them. Just like fans who ask for autographs in the bathroom when their fave just took a dump.
Sorry, but I think Rihanna handled it very nicely. She was obviously not having a good day, and yeah it sucks the girl didn't get her autograph, but she'll get over it. At least she got to be right next to her. She should be greatful.