Plus Google com not in referer log

Just tested it myself

[jetteroheller]

Why can I not see plus.google.com in my referer log file?

I just tested in plug.google.com myself a link to my web site,
but I can not see it in the referer log file.

[bhartzer]

I just check my web analytics and it does look something like:

plus.google.com/url?sa=

when it appears. I just saw it a few minutes ago.