The sign fairy, er, the evil sign fairy put it there.
I don't know if I believe this - probably just telling the candidate what he wants to hear....
From the NDP candidate's blog.
In the past two days alone Paul has spoken with at least two different people who had liberal signs on their lawns that actually weren't supporting Mahoney. In fact both of these voters told Paul that they were leaning towards voting NDP. They said they hadn't actually requested a sign and that a liberal sign had just appeared on their lawn without their consent.
From the NDP candidate's blog.