What's annoying is it's not the kind of thing I can avoid by not moving much, as it's not associated with the extremes of my range of motion. I can just be sitting there, twitch in the wrong way, and then be whimpering in pain.
This coupled with last weekend in Vegas, when I had a random back spasm - ow. Sudden attack of old. As Andrei's been saying, "welcome to your Saturn return." (But I thought I had another year, dammit....)