Ok, pulled all the spacers. Wire brushed all the surfaces and removed one sticker+residue on a front spacer (not sure why it was there...). Put a level on all 5 bolts each time I took them out. Noted one of the front ones was about 1mm short, but that's it. Had some brake pad antisqueal lying around so used that on all faces. We'll see how it does tomorrow. Perhaps I was just paying more attention than I usually do and the vibration has always been there. It didn't seem consistent either. Perhaps spacers accentuate road imperfections more?