It happened to me once though they didn't do anything as gmail realized their ip was from China and I was logging from NJ at the same time. I guess "password1234" is not a good idea.
It was funny cause like 2 hours before I saw that I was telling my friend about this like hacking war between china and hella countries. I wonder how they did that because I am pretty good at noticing phishing scams.
Brute force probably. I don't use my gmail password anywhere else and I use gmail notifier to log on. China nationalists have been hacking into gmail for human rights activists' info for quite a while.