Given your scenerio, I suggest that you find a repair shop that has a fiberscope. With one, a technician can look inside the suspect cylinder and probably see if a valve is bent.

Consider this,
If the valves are closed when the piston rises in a cylinder full of fluid, the piston will stop, the closed valves are unlikely to bend.
If either valve is open when the piston rises in a cylinder full of fluid, the liquid escapes out the open valve.

I'd be curious how a valve could be bent without mechanical contact.
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2 8s & 2 7s 600,000 miles total