I had two kittens a few years ago that had this weird habit. Every morning they would walk out to the center of the living room, circle each other for a few seconds and then fly at each other. They'd grab each other in mid air hissing and spitting, then as soon as they hit the floor they'd split, then start circling again. They'd keep this up for about ten minutes and then go off and resume normal kitten duties for the rest of the day. The strange thing is, they would only do this in the morning around 8am.