Every decade thinks that the "current" state of manners is worse than it was in decades previous. Because of this, I'm unwilling to say that we're definitely in the rudest period in history. It just feels like it. My theory is this: As more of our lives get lived virtually through our computers and smartphones, our ability to act appropriately in public diminishes, as we have less opportunity to use our "people skills." The more people you come across, the more likely you're going to experience a random act of rudeness.
And it's likely that the act is on the following list of incredibly rude actions that happen on a daily basis.