Well, Hemingway's writing career was long and diverse. He might have written a very short story at different points. It depends on your definition of 'very short'. Maybe in the 1920s or 1930s.
Hemingway wrote several short stories throughout his career. It's hard to pinpoint exactly when a 'very short' one was written. But some of his early works could be considered short.
To be precise, it's not straightforward to determine exactly when Hemingway wrote a very short story. His works span multiple decades, and many of his shorter pieces could fit the bill. It could have been anytime from his early days to later in his career.