Problem found!  It was a piece of orange gum that a visitor to our home had
discarded in a trash can in the bathroom. (The trash can was emptied before
they were released and our visitor didn't realize they were likely to
get in there after it.)  Anyway, it seems to have passed through safely.
"Lester" just passed what was normal stool with only a few flecks of gum in it.
Still eating and drinking normally and being watched very closely!
[Posted in FML issue 1211]