I ran it again and got this:
32 sectors had been re-allocated before the start of the preclear.
32 sectors are re-allocated at the end of the preclear,
the number of sectors re-allocated did not change.
I'm glad that the pre-clear didn't find any more sector to re-allocate, but I'm a little disturbed that the count went from 30 to 32 after the last pre-clear while the drive was sitting unused. I guess I'll go ahead and use the drive, but if anyone finds this really troubling, please let me know.