took a little shopping trip this weekend and all was fine on the way to the store. when we got in the car to head home I noticed a sound coming from under the hood. Hard to describe the sound, kinda sounds like a baseball card against a bike spoke. I immediately thought the fan was off balance but after inspecting it all is fine except a small chip taken out of one of the blades. I thought that was throwing off the balance but the fan appears to run fine and balanced with the engine running. Anyone have any ideas what could be causing this? It's running fine (no power loss, no overheating, no funny smells) other than the sound...ugh that sound!