[Flac] Something's driving me crazy

[inishmor]

I decode and then re-encode a FLAC file someone sent to me, and I get a different file (about 3K
larger).

I have used:
 - the same version of FLAC.EXE (hash-checked) used to create the original FLAC file
 - the same level of compression
 - no tag infos were included in the original FLAC file

I can't really figure out how could it be possible, but sometimes it happens (of course many times I
get exactly the same 'binary' file).

Any idea?

Thank you very much for attention.

All the best.
Stefano