Elton John recently got angry during performance and stormed off stage. He explained that he always has a group of fans come on stage at a certain part of the show and it's a "lovely" part of the show.
On this particular evening one fan was touching the piano keys and leaning over the piano to take pictures which Elton felt was disruptive and rude. So he left the stage until the fan, or maybe the whole group of them were removed from the stage.
Rudeness has unfortunately become an epidemic in our culture, perhaps because of too much reality TV, or more likely because we've lost respect for boundaries, each individual's right to control their life and space as much as possible.
To read more about Elton's explanation of his actions go here.