"I had to point out I wasn't on the subway in 1984, which is when she claimed she saw me," he added.
"And the reason I could prove she wasn't the woman in the song was that in 1984 I would have been 10 years old, and the first time I visited the States was in 2002. So that was all a bit strange."
The Goodbye My Lover singer said he's had several stalkers and obsessed fans over the years, but insisted he usually lets their actions slide because they shower him in "wonderful gifts".
Blunt even recalled one gift of "amazing box", which contained miniature versions of items from throughout his life.
Speaking to the Sun newspaper, he said it was like an "old airline pilot's flight case".
"Inside was a scaled-down copy of everything in my life - like scales I'm told to learn, a piano, a guitar.
"And on the walls were pictures of me as a child and books I'd said I'd read and all the albums I've ever put out or albums I've ever said I've listened to - basically my entire life in that box.
"I think the only thing that is missing from the box is me. One day I'm going to find myself shrunk and in the box."