I was recently relayed an odd episode. My friend was playing Feed the Beast's Monster pack (single player), mining away in the Nether, on peaceful mode, nothing unusual in sight, and suddenly there's an explosion.
Obvious culprits are TNT, exploding machines, and creepers. After verifying there was nothing like that around ("Are you sure you were on peaceful?"), I'm left stumped. I don't know every aspect of every mod in the pack, by far, but this seems odd to me.
What can cause spontaneous explosions in peaceful mode with no player setup?