There was probably a caterpillar or worm mixed in with the leaves when it was going through inspection. It's nothing to be alarmed about. Insects lay eggs onto leaves all the time before they fall off the trees.
Customs probably disposed of some of the infested ones and the rest of the package passed so they sent the remainder of the leaves to you.
You should send Amy a message to let her know.
- Singapore might have revised one of their numerous laws when it comes to exporting organic material.
- Or some caterpillars snuck into the area where she keeps the extra leaves.