Karthus Cooldown not reporting/operating properly

I am not real sure how to post game data or links. however, I was running karthus in game at 1/29/2015 at 12:12 EST on my account.
I was stacking Karthus with cooldowns and despite his cd timer reading properly as I could tell on my ult down to 96 seconds my actual cooldown timer was running at 150 timer plus and not reacting to my cooldown reduction I was stacking at all. I think there is a small bug inside Karthus at the moment as I've not had this problem elsewise if my logs are needed I will be glad to help if contacted or otherwise.

Ty, Indeoque