To stop Gmail accounts from getting stolen from their real owners, Google is starting to send notifications to Gmail members whose accounts they think are being compromised. This is in response to the increasing problem on Gmail abuse through various suspicious login activity by unathorized access to Gmail accounts.
When your Gmail account seems to be compromised you’d see a warning sign at the bottom of your Gmail Inbox page saying “Warning: We believe your account was last accessed from…” Google will also tell you the geographic region that it can best associate with the access.
When you get the message alert, you can click on the “Details” link next to the message to see the last activity on your account. From there you can see whether indeed your Gmail account was compromised, so you can immediately do the necessary steps to stop it. Of course if you are indeed travelling from one country to another and accessing your Gmail account then you can always dismiss the message.