Rod of Ages only showing 9 stacks?

So I was playing an ARAM game as Anivia, and I bough Rod of Ages. After a while, I noticed that my Rod was only at 9 stacks, even though it had been more than enough time. When I read the tooltip, it showed that I had the stats from a fully stacked Rod, however it said only 9 stacks. Just a small visual bug?