Player placed leaves are decaying. Tested in creative. Not survival.

I was in creative and I was designing a house for survival. I thought leaves would be a nice touch. A few moments after placing them they started to decay. NOT TESTED IN SURVIVAL!

What I expected to happen was the player placed leaves would stay upon placing until manually removed.

What actually happened was no longer than 5 minutes the leaves started to decay after I placed them.

Steps to Reproduce
1. Make/enter a creative world.
2. Place down some leaves.
3. Wait for them to decay.