OBA Burnout

That the problem was indeed OBA burnout and not a contaminant issue can be confirmed easily with a backlight. Inexpensive blacklights can be purchased at most hardware stores. If OBA burnout, the print surface will glow brighter under the blacklight where the print was protected, and signiificantly less where the OBAs have faded.

Light wouldn't necessarily be the culprit causing OBA fading. Low levels of ozone gas in the car interior could have caused the OBA burnout even faster than light exposure!

regards,
Mark
http://www.aardenburg-imaging.com