Nah. If you know just one person acted on this information in a way that caused harm (say you were fired), that would be sufficient. If one person asked, and then spread the information causing harm and backlash that would be sufficient (both the originator and the reproducer would be liable).

Furthermore, some statements like accusing someone of a serious crime are considered libel per-se and you don't need to show harm. You do still need to show the other elements of libel.