That was going to be my guess.

And of course I listened for it yesterday after work and this morning, and I didn't hear it.

Ya, it always works out like that. Will'* last post made me think of a mysterious clicking in a 91 LaSabre I had. Never did figure it out at the time, but reading his post, it was near or at that point.

This was my initial thought as well. It seemed that after my ABS box started going south, the sound stopped.

Aside form the ABS system, disk brakes are depressingly simple. Apply the brakes and simple hydraulic pressure in the brake cylinder pushes the piston and pad against the rotor. Release and the pressure bleeds back into the lines, leaving the pad against the rotor. Irregularites in the rotor will push the pad back slightly, but it will still rest just barely brushing the rotor. No adjusters are necessary.

I should have worded it differently, I was thinking more of something to do with the ABS system like someone else mentioned, not adjusters in the drum brake sense.