This is likely correct behavior. There hasn't been a ruling on it yet, but if you look at Foul-Tongue Invocation with it's similar wording, we do have a ruling.
Foul-Tongue Invocation {2}{B}
Instant
As an additional cost to cast this spell, you may reveal a Dragon card from your hand.
Target player sacrifices a creature. If you revealed a Dragon card
or controlled a Dragon as you cast this spell, you gain 4 life.
- If one of these spells is copied, the controller of the copy will get the “Dragon bonus” only if a Dragon card was revealed as an additional cost. The copy wasn’t cast, so whether you controlled a Dragon won’t matter.(2015-02-25)