This is set to 1 when the player claims the coin reward from the Getting Ahead quest.
If the player had a full inventory at the end of the quest (RS:Varbit/693 with a value of 34), this remains at 0. In such scenario, talking to Gordon after the quest with free inventory space for coins will reward the player 3,000 coins and set this to 1:
Hello again. Thank you for dealing with that beast.[confirmation needed] There is no other indication when Gordon holds a reward for the player.
This does not affect the quest log.