Yeah, I was looking exactly at it...
The different bytes are exactly the timestamp, which is obviously different --- since I "modified" the file while decompressing-adding .gz-recompressing.
Still, in the process, I learnt that the dictionary was created under *nix, if the OS field was properly set
Now I wonder what I did to get 5 out of 7 to recompress EXACTLY with the same timestamp... mmm... the MTIME field description says:
MTIME (Modification TIME)
This gives the most recent modification time of the original
file being compressed. The time is in Unix format, i.e.,
seconds since 00:00:00 GMT, Jan. 1, 1970. (Note that this
may cause problems for MS-DOS and other systems that use
local rather than Universal time.) If the compressed data
did not come from a file, MTIME is set to the time at which
compression started. MTIME = 0 means no time stamp is
Ok, perhaps I forced gunzip to ignore the fact that si.html did not have .gz extension, and recompress it "as it was", hence retaining the original MTIME.
Edit: CONFIRMED, this was the reason! Meh!