Summoner spell CD is bugged somewhere.

I just played a game with all possible summoner spell CDR available (40%), and had a 216s timer on flash. It's only supposed to be 180s? (at least i strongly believe that 60% of 300 is 180 :b

Seems like some of the CDR is CDR of the new value you got from your already purchased CDR, and normal CDR doesn't work like that, so i can't think that summoner spell CDR should work like that for any reason.