I see this behavior with brim all the time!
Hi WFNC,
I don't often run across crappie in my fly fishing ventures so I've never seen this behavior from from crappie. My own experience has been that rolling behavior occurs all the time with brim, They will actually roll their bodies across a Gurgle Pop as if they are trying to sink it. Once underwater, the brim and his friends toy with and nip at the fly but seldom give you a good bite that results in a hookup. Sometimes the brim will tail swat a fly which results in a loud splash but no hookup either. Obviously the fish are not hungry but still very active. I've written several threads about this behavior and gotten some interesting ideas but no definitive explanation. 8T :)