Report Colors Not Preserved When Exported To PDF

I have an oldie-but-a-goodie report that has some special color formatting on it to highlight dates of interest (green good, red bad, yellow coming up, blue can wait, etc.). However, one of my clients pointed out to me that when the information is exported to pdf, the colors are "off", as below. I'm tempted to rebuild it and see if that "clears it", but with hundreds of such reports, would rather find a less intensive workaround.

Anyone else had this problem and/or know of a solution?

Regards,

Doug