Not necessarily.
Depends on the board material, and whether the color is inherent or the result of the addition of a colored filler and/or pigment.
This link shows the QSC substrate pretty clearly:
The tip-off that this isn't paper/phenolic is the cloth pattern.
I did a little research and found a commercial non-phenolic material that had an essentially identical appearance.
This is all in the AAPLS google archives from a month or two ago.