Bug with octave check

[Geoff Horton]

I was doing an octave check for "c" when the actual pitch in the
output was "c,".

The resulting error message tells me:
warning: octave check failed; expected c, found: c,

I know what it means, but it's very easy to misconstrue (especially if
the piece had been more complicated). Would it be possible (and
helpful) to add quotation marks to the error message, as I did in the
first line of this message?