When breaking stone (may occur with other blocks) there is a short delay, you have to wait about 1 or 2 seconds for the broken block to disappear. Same problem happens when placing blocks.

gatharian added:
Tested by quickly placing or breaking blocks in a Village will produce the delay. (i.e. Breaking a villagers house or quickly placing blocks on the ground in the village.) Seed for testing that has a village: 1388582293