What I expected to happen was

When I was confronted by a creeper, I expected it to blow up immediately after hissing.

What actually happened was:

Instead, it had a delay before exploding after the hiss noises.

Steps to Reproduce:
1. Go in survival mode.
2. Find a creeper.
3. Hit it multiple times while it's hissing.
4. Note that sometimes you may have to reproduce the bug again. Like I said in the title, they only do it sometimes. Not all the time.

Thanks for reading and have a great day.