lot of play and prey --- dog is having fun -- decoy not putting up much challenge - giving dog the sleeve quickly.
how is her obedience ? does stress show there ?
you could continue at this level as long as you see the dog , and yourself having fun -- but I wouldn't want to see this dog pitted against a stronger decoy which may reverse things and create a problem.
At this level she isn't in fear or avoidance , but is at the level which is still okay for her --
you can't correct nerves -- you have discovered her level , training does expose this