Horn lines in Garage band

I recorded a piece using the trumpets in garageband. Somehow, the horn riff would "roll down" at the end, i.e. it was as if the trumpeter, after playing the note, would let the note fall as it died out. Is this making any sense? Anyway, the effect was marvelous, but I cannot for the life of me replicate it. Anyone have any experience with this? Any help would be appreciated.