I have a set of Harland Sharp roller rockers and they don't have those stinkin spring things that are supposed to keep the rockers on top of the valve stem. There are billet aluminum spacers between the rockers on mine so they don't slip off the valve stem like yours did. They are shimmed to fit properly. I think there are other mfgs roller rockers that are built that way too.
The combination of revs and valve springs allow some lateral freedom that can allow those spring centering things to let the rocker move off the valve stem. That's what I see in your picture. It may have bent the pushrod too in it's trip off to the side.
Here's the Summit part that I have:
http://store.summitracing.com/partde...K&autoview=sku
Cheap valve gear is poor economy.
Paul