Well, the first batch of homebrew I made was a saison I called "Bras D'Or", or "Golden Arm."
Want to guess why?
The rubber grommet fell in just as happened to you. Not knowing what to do, and not knowing any better, I washed and sanitized my hand and arm...and reached in. I found the grommet, and the beer turned out so well that I am fully addicted to homebrewing.
Now, that was during primary fermentation, and it was a warm fermentation with a particularly voracious saison yeast (Wyeast 3711), so perhaps not for every one.
I have since resisted the temptation to dunk my arm in every batch I brew, but should you decide to go fishing, you won't have been the first.