I normally do the rolls for initiative, perception and various little rolls and saves as the game goes through, but this is a new crew and I had not gone over what I normally roll. I didn't want to start the game on someone's toes so to speak. Therefore I will roll initiative and perception rolls in the future. Many reflex saves and such that the result may leave the information hidden, such as did you step far enough onto the trap to set it off, or is it still lurking. Did the elf notice the secret door? This kind of information, though opposed checks outside of discovering the ambush of another (contested Hide vs. Perception roll), should normally be yours to make.