problem uploading files to Squeakmap

Today I've tried to upload to my squeakmap account a new sar package
with some bug fixes.
This sar file has a 27 kb size, but after loading it to SqueakMap it's
37 Kb. Obviously, downloading it I get a bad file that can not be
unziped.
Trying to guess if it was a "strange" fault in the sar file, I
downloaded one of the files that were in my squeakmap account, renamed
it and uploaded it again. And, the new file was also 12 kb bigger than
the original one.
Has anyone else reproduced this problem? any solution for it?

P.S.: I almost forgot it: I have checked the same behaviour using
firefox, opera and lynx, so it doesn't seem to be a browser related
problem.