You're just likely going mad. The 250 tier was added after the first tiers were added though so if you completed quests during the period of time after the achievement was released but before the 250 was released they would count.

Yeah to what Jordan said.. The system still counting after you finish an achievement.. for example: if you will make your 11th scroll after you got the last tier, it will count and when they will add a new tier, you will see the count as 11/??

That'll be what I remember then, got confused. :P Lol thanks. :3