I have the same issue and traced it to a rubber capped switch on the passenger side of the hood, about 12 inches back from the front edge. I'm not sure what the switch is for. There is a complementary rubber bumper on the hood which depresses the switch when closed. I removed the bumper as a diagnostic technique, shut the hood and the noise went away. I put it back in, shut it and it came back. I'm going to the dealer tomorrow. Somthing needs to be replaced as even when I put a towel between the two surfaces, it still squeaked.