Odd failure

At the start of yesterday's club ride, a good friend had taken her bike out of her hatchback as usual, slipped the front wheel into the forks as usual, and tightened the quick release. She said she heard a "ping." Then her quick release felt funny, in that it had lost it's "over center" clamp action.
Several guys fussed with it, trying to determine what had gone wrong. The fundamental clamp action still worked, just not the over-center action. We pulled the skewer out and saw no visible problem.
Ultimately, we clamped it, pounded as hard as we could on the top of the tire as she held up the front wheel, pushed as hard as possible side to side on the wheel, and proclaimed it rideable.
She completed the 35+ mile ride just fine with the wheel still tight in the forks. But I suggested she follow me home so I could donate a spare skewer, plus take hers apart to see what might have happened in there.
When I disassembled the skewer's lever action, here's what I found: The left or lever end of the skewer features a steel cylinder maybe 1/2" diameter and ~1/2" long, drilled with a transverse hole ~3/8" diameter. The circular eccentric surface of the lever operates inside that hole, applying leftward force to put the skewer in tension. (Most of us probably knew all that.)
In her case, the metal between the side wall of the transverse hole and the outer surface of the 1/2" cylinder failed in tension, doubtlessly due to fatigue. That caused enough deformation to remove the over-center action. The other side wall held and provided clamping tension. I think it was important that the cylindrical end piece is a pretty close fit in the thick chrome "nut" in which the lever pivots, so serious bending action on the remaining metal wasn't possible.
I'd never seen that sort of failure before, and neither had my bike mechanic buddies. I wonder if others here (especially Andrew) had.
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- Frank Krygowski