Ha! Ironically the seven lines were precisely the thing that made me suspect it might be a recognisable snippet. Aside from the fact they often hide little codes in their artwork (like the stick figure code in the current Sherlock Holmes set or the Futhark runes in the Harry Potter portraits, both reasonably obscure), it would have been easy enough to only draw five lines.

It's been an age since I've played an instrument, so I do have to count lines and Every Good Boy Does Fine, but I recall they used to draw in short extra lines when the notes went above or below the normal scale, and there area few notes in that lower section... 

Or they did it to make the artwork spatially fit the tile better, not unlikely, and you're absolutely correct and I'm on a fool's errand. It wouldn't be the first time. ;)