Possible Kindred W bug

I had 40% cooldown on kindred and max level W so the cooldown on it was 8.4 seconds. Wolf's frenzy (W) lasts for 8 seconds but when ever W ended, the cooldown on it would start at 4 seconds instead of 0.4. Not sure if this is intended or not but it doesn't seem to make senses because if the cooldown starts right after you use the ability or starts after the ability ends then I should be getting a cooldown of 0.4 seconds or 8.4 seconds instead of just 4 seconds between the use of the skill.