like Pix said without a screen shot it is hard to tell what you are talking about.
If you are talking about a yellow line that has just 'appeared' it could be the selected layer.
Layer below is larger than the one above in the above picture.
[attachment=8094]
Layer below is smaller than the one above in the picture below.
[attachment=8094]
Layer below is smaller than the one above in the picture below.
[attachment=8093]
