There is another thing it could be, the tensioner "prints" onto the belt a thin line in the centre where the tensioner doesn't touch being made from two "halves" sandwiched together I've seen people blame this on touching the stat housing, just in case the turning the other way doesn't cure it, not paid much attention to bow close they are on the 4wd, but know on my 2wd it doesn't touch when turned either way, looks nicer though if the run between the left cam pulley and the tensioner is parallel to the top belt run between the pulleys.
tabetha