[davepl]

Can't speak to the cause, but at the risk of pointing out the obvious, you're still missing a piece of that pushrod, are you not? So long as it's not in the engine somewhere...

Ignition timing couldn't bend a pushrod, at least not in any way that I can envision.

I wonder if gunk got into the lifter, plugged it up, it wouldn't compress, and that bent it. That's my best guess... gummed up lifter. If a chunk of carbon gets stuck in the valve that can also do it.

Check the bottom of that lifter for condition - if there's any suspect wear on that lifter, you likely have some on the cam as well.