Not if you weren't using it. The POP3 implementation would have to have a serious security hole that allowed bruteforcing a password or something like that.
This is exactly the accusation I am making: That Gmail's POP3 interface is inadequately protected against brute force attacks from China.
If you think about it, it is kind of hard to do. At best you can throttle the number of attempts or lock the account after a few failed attempts.
They can't do the stuff that they do on the web UI, there is no way of popping up a "are you human" form after a few failed logins.
I don't think locking peoples' POP3/IMAP access after a bunch of failed logins from China would be received very well by the users.