Roll Call carries the most detailed account of the incident:
The confrontation began with the two talking in each other’s faces and gesturing animatedly with their hands. Obey then attempted to walk away, but Waters kept following him. Obey then put his hand on Waters arm and shoulder, and Waters became irate.
Obey again turned away, dismissing Waters by throwing up his hands, but Waters continued to stalk him, talking to his back and making a shoving motion.
Waters followed Obey down to the well of the House, and as the confrontation — and shoves — continued, Obey turned and told her: “You are out of line.”
To which Waters retorted: “You are out of line.”
“I am not going to approve that earmark!” Obey exclaimed, then hustled away from Waters.
Waters then retreated to a group of fellow members of the Congressional Black Caucus, but her conversation could be heard from the press gallery.
“He touched me first, he pushed me first!” she said. She the left the House floor, while Obey discussed the incident with House Majority Leader Steny Hoyer (D-Md.).
It's entirely possible that this affair will be settled quickly, with a mutual apology, and with Waters behaving like a grownup. The only thing stopping it is that Waters has never behaved like a grownup before.
So we have Rep. Alan Grayson shoving photographers, Rep. Tim Bishop running from constituents, New York State Senate Democrats locking their rivals out of the chamber, and now Waters and Obey fighting on the House floor. Do Democrats not understand that elected representatives are expected to maintain a minimum level of civility?