Did you rough up or replace the rotors too? They may just need bedding in too. About 50 miles or so of on/off braking will wear the pads enough to conform to the rotors. My tech school instructor had an acid test for brakes before installing the drum you grab hold of the shoes and snap them on the backing plate - nothing should fall off. On discs, you shake the caliper before you install the wheel. I've seen brake pins that guys though they had tightened down pop out.
If the anti-rattle spring is too easy to install it probably is worn out and will dissappear soon. AP stores sell brake kits that have the springs, guides, etc. for about 7 bucks.
