I did quite a bit of prep for Taos. I met my riding buddy just over the bridge at the Cape Cod Canal, about ten miles from my house. I told him I keep hearing a clunk when I use my back brake. On closer inspection, I saw the problem. When I installed the rear caliper, I neglected to put the bolt through the caliper assembly. You know, the one that keeps it from rotating.....The bolt was there, it just wasn't doing much.
DOH.
Good thing your bolt was still there. Lost mine, not sure why, took a week or so to get new one. Not a bolt you can run down to local hardware store to replace.