Is it just me? (Summoner spell bug?)

Lately this has happened 3 - 5 times to me. My barrier spell will be set to F and flash set to G. Right when I need it the most I press F to activate barrier (YES I KNOW WHERE MY FINGERS ARE I'M VERY AWARE OF MY KEYBOARDS LENGTH) and i end up flashing instead. Again, this has happened to me 3 - 5 times and has gotten me kill I don't know if its just a bug with barrier or not.