Gmail warning at top of screen that my a/c hacked?

I have a warning in a red toobar at the top of my gmail account saying it has been accessed from the USA and offering two buttons to click one to ignore and one to see what preferences there are?

Anyone experience of this or know if it is real/fake?

I have not done anything yet ie change password?

Sounds like it's legit. This might be of help:

http://gmailblog.blogspot.com/2010/03/detecting-suspicious-account-activity.html

Thanks that is exactly what it looked like....will change password now.

Check your account settings, and change your password immediately.

It might be that you logged on yourself from a location that was routed through the US, but if you don't think that's the case then...

It's a good idea to set up two - step verification, where gmail will ask you to enter a code it texts to your phone every time you log in from a new device.

I got that recently,I was in work when it happened (US Multi National)and its because that particular computers location was routed through the States if that makes sense.