I have a hint as to why that might be... you're moved to the next level when your torso is at least 32px off the right side of the screen. however, if you're 32px BELOW the bottom of the screen, it counts as a fail. It's not common since all levels end with your character at minimum 64px from the bottom, but if you exit slowly enough you could theoretically fall off the stage without clearing the 32px x-value. I can fix this tonight!