Henderson is set to lift the Premier League title in a matter of weeks after captaining the side to glory.
The arrival of Fabinho in 2018 gave him extra competition in midfield, particularly given that the Brazilian was their only natural holding midfielder.
"A year ago we had a conversation when Fabinho signed," Henderson told the Guardian.
"He was fantastic in that deeper role, definitely one of the best No 6s in the world, and it was an opportunity to move a little further forward.
"That was over a year ago, and since then I've played No 6 and No 8 as much as each other. It doesn't really matter."