Looks OK from here. There may be a MITM attack in progress against you (or the network you're on). This has happened in the past; could be a rogue WiFi AP, or your network provider, or even the government: http://googleonlinesecurity.blogspot.com/2011/08/update-on-a...
Not 'yet' valid? Check your system clock...I'm willing to bet it's set a few years in the past!