Well, your intuition was correct Klaus. When you said "a first!" you were saying this had never happened before. Well, turns out it still hasn't happened. I got to thinking about things, and realized that I hadn't cranked the engine during the time the hose had disintegrated. I think the local squirrels got it--whey they eat car parts, I don't know. But no risk of hose bits in the engine this way, at least.

Thanks for your reply--hose replaced, car started, all is well.