Google so big and professional also can have SSL problem?

When I was trying to access gmail to check my personal email in the evening, I received the following error message:

The server's security certificate is not yet valid? The leading search engine company also can problem with SSL? Initially I couldn't believe and thought is my own browser problem. I tried to Google Adwords and my company web mail (via gmail) also with the same error message but ok for other secure website! I was not dreaming. Really Google problem but actually from Google made the mistake? I believe this mistake will spoil the reputation of Google. Wondering will the person in charge get fired? Sorry to think so.

SSL or Secure Socket Layer is cryptographic protocols that provide security for communications over networks such as the Internet.It will encrypt the data transmitted over the Internet. To have SSL, you need to buy the certificate from provider such Verisign, Thawte, Comodo, etc. by paying yearly subscription basis. A website with SSL is called as secure website. To know whether a website is secure or not, just the web URL. A secure website is start with https not http.