Had my 2005 mazda6s for a while now and had no problems so far. Recently i noticed the CHECK ENGINE light comes on blinking when engine RPM reaches over 4000. When rpm drops to about 3000 and lower the light goes out. Car has about 20,000 miles on it and i don't think i saw this before. Anyone ever experienced anything like this? The car is still under warranty so i would like to have it checked out but i am not sure if the ECU retains any codes since the light goes out.