Is reading the Haftarah a Minhag?
I know that the practice was instituted when we couldn't publicly read torah, and then it was kept. Does that make it a Minhag?
משנה ברורה in ס' רפד ס'ק ב says that it began as a custom to say when public torah reading was banned, and was subsequently enacted as a גזרה. This would appear to be backed by earlier authorities, as רמ'א quotes תשובות הרמב'ן in that סימן describing the 'תקנה' of הפטרה, as opposed to just a מנהג.