BF quest items and monsters are placed randomly on the third levels of the dungeons, so it is possible for any particular dungeon to have none, one or multiple items or boss monsters. Since there are only 3 dungeons in the act 1 BF and 5 quests, it is not out of the ordinary to get 3 boss monsters at once.
The level of the monsters, however, was likely influenced by your stats. The level of the DK Patrols in the citadel, for example, will be higher if you clear out the surface and first dungeon in the BF to level up your characters. Apparently the game takes your stats into consideration, rather than just the character level, to account for boosts from permanent potions and maybe equipment. Since item quality also is effected, I would guess that the game calculates an 'effective level' from your stats, to use in gameplay balancing.
