Small Dripleaf sometimes shrink into smaller (1 block tall) Big Dripleaf when using bone meal

Using bonemeal on a Small Dripleaf would shrink the dripleaf and result in a one block tall Big Dripleaf. It appears when you bonemeal a Small Dripleaf, then the Big Dripleaf's size is supposed to increase a random amount. However there is a random chance it would actually shrink down to being one block tall.