The warning is permanent in the Settings app, it just leaves the lock screen and main Settings app page after four and fifteen days, respectively.i dont understand this logic. Ebay maybe, but If you get your phone repaired anywhere BUT apple, its not going to be a genuine part....
also, acording to the article, its only going to show the message for 4 days on screen, then 15 days in settings. whats preventing a seller from just waiting 15 days to sell the phone? Apple shouldn't have to force feed its consumers information they are too ignorant to figure out. Buying phones off ebay is a risk regardless of how many pop ups apple throws at you.