FYI.

It doesn't happen to me as much as others, I guess.

I access the site several times every day, usually with no problems (i.e., I'm already logged in when I access the site).

However, once or twice a week, I'm not logged in when I visit the site.

This only happens the first time I visit the site after booting up my computer in the AM.

I'm usually good for another week or so after logging in.

Computer: iMac running OS X Yosemite (10.10.1) and Safari 8.0.