If y'all read the other thread, I wrote about my experience of a trip to the ER with a bristle stuck in the back of my throat.
Several weeks ago a gal who works with my wife had to take her son to the ER, he swallowed one that got hung up in his esophogus. They got it out OK, but it wasn't a fun process.
Always check your grates before you put food on them and I 2nd the motion to oiling your grates after cleaning them.
One other thing, you can clean them with wadded up aluminum foil... but we all know the dangers that aluminum foil pose