My 2003 BMW makes a chirping noise when I turn of the engine after useing the car for over 10 miles or so.

sound like its leaking something, or like drops of heavy water. Ive heard it could be a miss aligned belt. It is still under warranty and took it to my dealer ( irvine BMW) and they said they couldnt find anything wrong woth the car, nor hear anything...

WTF should i do? what is it? should i go to another mechanic and see whats up? thanks....