Hopefully you didn't click the link that came with the message, which was part of a Twitter phishing attack to steal users' passwords and then spam their followers with the same password-lifting link.
Since it's unlikely that a U.K. cabinet minister would a) tweet something so sexy, and b) misspell the word, "hey," the fake tweet was easy to spot. Many people who got Miliband's message probably knew about the phishing scam and didn't click the link the message contained. Or they've tweeted long enough to know that poorly written messages from people you follow are bad news and are to be ignored.
Of course, in order to have that phishing message sent from your Twitter account, that means you probably clicked it yourself. That's how phishing works. So we're not saying Miliband clicked on that link or something similar, but…
Miliband tweeted later, "Oh dear it seems like I've fallen victim to Twitter's latest 'phishing' scam."
Hope he changed his password.