Like Jim said, the rebound adjuster effects both compression and rebound. However, if you achieved these problems in roots and rocks it wouldn't have much of an effect in this situation.
What was most likely happening is it was falling lower in the stroke. Normally roots and rocks at a decent speed can cause packing quickly especially with the rebound at 5 out. The compression is keeping it up in the stroke, as well as the rebound. That keeps it up in the stroke which generates the softer feel.