Since a few months ago, all Google web apps have been telling me that they suspect suspicious activity on my account:
"Warning: Someone signed in to your account from a different location. Was it you?"
It is always one of my own computers/logins. The Google support page says to click the "Yes that was me!" button. I have used this button before, but it now appears to have vanished.
Note that I do not want to disable the warning - I want it to learn about my existing logins/locations. This system is now training people to ignore the warning.