Are Hybrid Spells Cast With Only One Mana Color Still Multicolored?

Derek casts Nightveil Specter using only Blue Mana

Do I still gain the one life?

The Gatherer seems pretty clear on this one:
  • 9/15/2013: Most hybrid spells and permanents, including the ones in the Return to Ravnica block, are multicolored, even if you cast them with one color of mana.