2000 Pontiac Sunfire Bent Pushrods in 4 cylinder 2000 Ponti

We sold our 2000 Pontiac Sunfire to a friend. Thwe car had 48,000 miles on the odometer. Our friends took it and somewhere between our house and theirs the car died. They called us the next morning, saying they ran out of gas, filled it and then it would not start. I went over and I could not get it running. We towed it home and gave them their money back. We sold it a few days later 'as is' to this other friend who is a Pontiac guy. He ended up replacing the pushriods which he found were bent and were keeping the engine from starting. Now it runs fine.

My questions is this: What could the first buyer have done to this car in the 12 hours they had it that would bend the pushrods? It was running perfectly when I washed it prior to letting the first buyer take it home.