Smite is weird lol

Tonight I was just walking through the jungle as Ahri and I looked at my current stacks for the new smite item and well... I had 800 stacks on devoriers. It corrected itself and when back to 1 after I killed red buff But I just found it weird I had over 800 stacks on the smite item. lol

I'm not sure how the stacks affect when you smite a champion, I never got a chance. If it happens again I'll try to get a screen shot or picture.