Runes - not receiving 10% CDR at 10 min

So I only just noticed this in my last game, but for some reason I didn't get the 10% CDR from the new runes until about 17 minutes into the game. One thing that I noticed was that I had blue buff going into the 10 minute mark, which was the only CDR that I had at the time. Wondering if that might be causing the bug or something...