could be a zillion reasons why they got dug. WQ says it most of it- but soft dirt, different colored dirt, too small a pattern, animal felt trap under foot are just a couple more.
Also- it is very rare for a coon to scratch, dig to expose a corner of a trap. Very rare. A coon wil ltotally uncover a trap , often overturning it and setting it aside unfired. Coon dig for food, canines dig at the trap usually from curiosity.