Trialtracker Scout and Burnished Hart interaction.

I recently got one of the Bloomburrow decks from my local gaming store and have been doing a few test turns with it to get a feel for the deck and have just come across this situation and need help to determine whether this works as I think it might.

I used 3 mana to sacrifice Burnished Hart for its effect to search 2 basic lands. This triggered my trailtracker scout to return a target permanent in the graveyard to the hand as this was the 8th mana expended this turn. Can I then target Burnished Hart in my graveyard to return it to hand with trailtracker scout or is it not a valid target yet?