Have an 87 GN...41K miles...original paint...I keep it covered in the garage...when it sits for while the front bumper fillers get this dull haze on them...and it's not easy to get off...I take a wet towel but all it does is smear it...then I take a spray detailer wax and eventually the filler looks new again...just takes a while and a lot of elbow grease...so what causes this haze and is there any easy/quick way to get it off without hurting the paint...