FYI, connect supports a shorthand syntax for method binding. Just pass an object full of action creators instead of a mapDispatch function, and you will get those action creators bound up, as props. For example:
const actions = {onDeleteFlashMessage : deleteFlashMessage});
export default connect(null, actions)(MyComponent);
Overall, I prefer to define separate action creators outside of mapDispatch, and bind them using the shorthand syntax. That also makes the functions more reusable and testable.
I talk about this a bit in my blog post on Idiomatic Redux: Why Use Action Creators?.