Super Smash Bros. Brawl- Lucas move?

I'm pretty new to Smash. I played Melee maybe a half dozen times but I'm getting into Brawl now and play mostly Lucas and Marth. Recently I was playing Lucas vs. Lucas and noticed the other Lucas did a roll very similar to Samus' where he was tucked in and rolled through the air. In the next match I was trying to figure out if I could do it and managed to do it once with some on mashing but can't seem to re-do it. Can someone tell me about this move, or did I just pick up an item I wasn't aware of?