[hamjet]

it very well could have been a stuck valve. imagine for a moment if the valve did not close all the way you will have a lot of clearance which can allow the rocker to flop at an angle, once the lobe takes up slack, if the rocker hit the valve on the edge, it would put pressure on the pushrod at an angle. looking at the pushrod in the photo it looks like it bent right at the wear spot where it comes through the head.