WorldBorder keeps moving when the game is stopped

What I expected to happen was...:
that worldborder will stop

What actually happened was...:
worldborder continues to move to the desired radius

Steps to Reproduce:
1. /worldborder center ~ ~
2. /worldborder set 10
3. /worldborder set 1 20
4. Press Escape
5. Wait a few seconds and you will see that the barrier has changed