There is a plastic "snapping" feature (Two plastic tabs that when pressed together can fit into the holes on the spray arm. Once in there, the tabs expands and keep the spray arm in place) that comes out of the top onto which the spray arm is attached to. That plastic piece broke and the spray arm fell off.
It wasn't clear how the snapping feature was attached to the top of the dishwasher at first. I was looking for a replacement for it and could not find it on any of the assembly diagram online. Then I came across a post on AppliancePartsPros that the piece comes with the 3RD Level Pray Arm Assembly. http://forum.appliancepartspros.com/dishwasher-repair/32875-replacing-ge-3rd-level-spray-arm.html (Note, the part picture does not show the side which has the center hole and the snapping piece that clip to the hole).
I have to pull out the dishwasher from underneath the counter top and unscrew it from the outside. Once that's clear, it was very easy to order the spray arm from AppliancePartsPros and just do it. It works perfectly.