I filled a village with TNT. I ignited a block and flew away ≈30 blocks. When I went to examine the damage, it appeared that much of the village and TNT were still there. I placed a stone block on one of the TNT and was about to place a lever, but the TNT block I right-clicked on to place the Stone was gone. THis was the case for the entire village and much of the area surrounding it.

Steps to Reproduce:
1. Place many (about 400 in my case) blocks of TNT
2. Ignite one
3. Fly away before it explodes.

I haven't been able to intentionally reproduce this, but it has happened to me four times now, from 1.1 to 1.4.2