FOP 0.91 : "trying to remove a non-trailing word space"

Has anyone else observed the following message when generating
PDFs from FOP 0.91? -

  trying to remove a non-trailing word space

Any idea what kind of problem (if any) it indicates? Any clues on
how to avoid it and/or how to suppress the message? It seems to
just be a notification. But it appears even when FOP is run with
the "-q" (quiet) option.

  --Mike