I read online that they were having some technical difficulties and doing maintenance. Apparently it’s affected only a small amount of users. I haven’t had any issues (yet). They mentioned it on their twitter feed: http://twitter.com/#!/gmail
I have 4 gmail accounts. One was affected. Spouse has only one and it was affected. So that’s 2 of 5, or 40%. Not a “minimal” number of users if we’re a good random sample.