perhaps they were referring to that the image was not exposed properly(either overexposed or underexposed) may be  too contrasty  or lacking  of contrast,but obviously something to do with exposure so if you think you can not correct it by  re-editing it then it'd be better to retake.
good luck
edit:also you know they are not so keen on harsh shadows  and unwanted reflections

Is is not possible to fix exposure in PS, without the need to return back to a shooting location? Especially, if the location is on some other continent.