Thanks for the info fellas! I'll look into the ABS and VSS stuff.

I took them apart and cleaned/inspected them. Runout was 0.002" on the driver's side and 0.003" on the pass side. That's on the high side of spec so maybe that could explain it since its really light vibrations. It was hard to measure though with the slots.

Another thing I've noticed since I installed the "upgraded" slide pins is that the one with the rubber on it is always crazy tight after a while. When I first grease it up and install it its not bad. But its only been ~4k miles since I last did that and it was really hard to remove. Anybody else have this? I don't think it explains the vibes but it seems wrong to me.

Maybe I'll try getting my rotors turned...?