Seems like a lot of users on cryptopia trollbox is complaining about the same issue so this isn't an isolated issue.

I wonder if this is related to the recent email hack that resulted in 100 million+ email addresses as well as some passwords being hacked. It could be possible, but then it could be just some phishing attack that got around recently.

The 4chan user had emails sent to him about login failures, which means that they may not know the actual password of the account. But somehow, he broke into your account which is even weirder. Contact cryptopia support to see what they can do for you.