It would be nice to have a timestamp in a gstat report otherwise it is necessary to rely on the file creation date, which is not always correct.
This could be the first line of gstat output, just before the Database "/path/to/my.fdb" line.
Perhaps something like
Gstat execution time Sep 30, 2017 12:00:00
I would guess that this might be easy enough to add to 2.5.8, 30.3 and 4.0
It might also be useful to add a timestamp at the end of the output as large databases can take quite a while to analyse.