Imagine my total shock when I discovered this afternoon that all four pins and retaining clips are missing on the rear wheel calipers on my 1995 940.

I redid the rear brakes myself about 2 years ago, and I was under the impression that the Volvo rear caliper design was foolproof and could be counted on to last for years. I used all new Bosch parts for the brake replacement kit... pins, springs, etc. I figured I did it all correctly... tapping the pins to snap home firmly.

So WHAT in the world could have happened that the pins from both the rear left and right brakes could have the pins totally fall out?
I had Costco replace the tires about 2 months ago, so I don't know if they would have noticed then or not.

But in the meantime I drove this car up and down Mt. Rainier! I shudder to think about driving it with no pins in the rear brakes.

I'm having my indy mechanic do this new brake job... I don't trust myself just now, considering I don't have a clue why it happened.
Does this sound like a completely odd thing to happen to the rear brake pins and hardware?

I'm baffled and shocked.