In fact they put so much effort into the whole affair that they managed to list a different song than the one they were complaining about. From a completely different band even.
Eventually the matter was cleared up and the IFPI sent what could only be described as an apology in the loosest sense of the word. Here's the text of the letter.
"IFPI was contacted by a member of the label who confirmed you were given permission to post the file on your site.
We were unaware of this agreement but now that it has been notified to us please feel free to upload the file.
Due to the volume of infringing content we find online there will be instances where legitimate files are picked up as infringing. We hope this matter shows that once we have the correct information we do not want to stop the promotion of music online."
In other words the IFPI has decided to appoint themselves as a clearinghouse of copyright licensing, and if you want to license music from labels they represent you'd better be prepared to prove it to them.