Sometimes creepers will either not emit their sizzling sound before exploding or will sizzle but explode too early. This lead to a completely unfair death that I could not have possibly reacted to. Currently I can't find a way to reproduce it other than by pure chance. However, it may have to do with the creeper taking damage and attempting to explode at the same time, as this usually happens in ravines if the creeper falls high enough to take damage. I only saw one report from 1.7.2 marked as resolved, but no action was taken to fix this bug.