hi, driving my UP today I noticed that when I roll the window down by about 1/3 there is a sound - its like a fluttering sound, as if there was a piece of paper stuck in the window. I've checked and there isn't anything stuck. The sound isn't there when it's only open a little or when it's about about 2/3 but it seems the 1/3 opening is the trigger for this noise!Anyone else experienced this?