Bent pushrod, what is the cause?!

Usually when they bend it's because of some kinda interference issue. Piston to valve is the first thing that comes to mind. When I first got my 65 Valiant years ago, it had a skip. Turns out it was a bent pushrod. I pulled it out, put it on a vise and beat it straight with a ball peen hammer. Put it back in and adjusted the valves and never had another problem with it. Go figure.