I asked the same question on another forum and it sparked an interesting discussion:
Cherry leaves and wood | The Gerbil Forum
In short, in the absence of more information it's probably best to avoid feeding cherry leaves, especially ones picked and processed at home as commercial companies like Hugro may have special procedures that render the leaves safe.
The only part of the cherry tree that is definitely safe is the de-stoned fruit.
You can safely feed strawberry, raspberry and blackberry leaves.