I just received my new refurbished Epson 4990 from Epson. I cleaned the top of the glass with lens cleaner. However, when the scanner is on and the light is shining from below, there appears to be a haze on the inside of the glass. When the scanner is turned off the glass seems to look very clear and clean. Do I have a problem here and need to return the scanner for another? I just scanned a color photo and it looks good. Thanks for your advice.