Yes, it's normal. There's a 1/80,000 chance a monster can drop it, regardless of game stage.(1/8000 in expert mode) To avoid future confusion, here are the items that can drop on ultra rare occasion :
1. Da Dude's Holy Blade
2. Layzhor
3. ILSS
4. 360 No-Scope
5. Orange's Discipline Tool
6...