I've had several creepers blow up holes around my villager area and iron farm. At first I was confused but then I was pretty irritated to find that a creeper had blown up a hole right beside my iron farm. There is no way the creeper could have blown up because I am underground, in my very well lit villager trading hall, and I am at Y level 40. I have never heard of a creeper blowing up for any other reason than being a player interaction such as the creeper exploding naturally or the player using a flint and steel. I do have a bunch of iron golems that sometimes fall out of my farm. My best guess is that the golem tried to attack a skeleton and then the skeletons arrow shot a creeper and the creeper blew up. But I figured I'd report this anyways.