This has happened to many of us. In August I was in Malaysia, doing one of my street shoots of old buildings. During a rain squall I poked my Nikon D800 with the 28/2.8 D and a Nikon lens hood through a wire fence to quickly photograph something, and I didn't notice that the hood fell off.
Got almost down the street and under shelter when I realized it. There followed an agony-inducing wait of about 35 minutes until the rain stopped.
I then went back and hopped the fence (to a derelict 1940s cinema with a parking lot overgrown with tall grass and bushes) and fossicked about for the next half hour. No luck.
Went back to my hotel feeling much worse than I should have. Those hoods can easily be bought on Ebay for +/- AUD $20-$30, so it wasn't the end of my world. But I wanted that one Out of pride, maybe. Or obstinacy.
The next day I returned, went over the fence again, looked for maybe a minute - and there it was, lying in wait on top of a bunch of grass I was sure I had checked the day before.
Finding that darn hood really made my day.
Another small aside. A few years ago I lost a plastic Panasonic Lumix 14-42 hood on the main street in my home town in Australia. I realized it was missing after a few minutes, and retraced my steps - just in time to see a laundry truck drive over it. Gone!!
Now I use the aforementioned Nikon '28 hood on my Lumix 14-42. Both are 52 diameter...
Great to know you had the same spot of sheer luck with your Leitz lens front. Those wee small moments do matter.