Oh and I did have unique and set items at level 13...
If you had unique (rarity) items at level 13, then it was probably a bug. Are you sure? They're the ones with the dark-red names (one step higher than Epic) that have 3 instrinsic powers, 3 charm slots and 3 enchant slots. I didn't find any until FoV (around level 40) and even then, they were pretty rare.
I think you might be confused with unique equippable quest items like the crystal skull - they're different to the unique (rarity) items.
