One of my villagers found a badger vest lying on the ground in the town square. I opened my equipment window and realized it was my vest, in the slot where I had worn it there was now a bloated leech!
I had visited a swamp sometime earlier and had likely picked up a leech or two, so what I suspect happened is that when the leech changed to bloated, some glitch put it in the wrong slot, which made the item currently equipped there drop to the floor. Luckily for me this happened where someone could easily find it, and it wasn't something particularly valuable. But there seems to be a risk of losing very valuable, hard to replace gear this way.