I believe the threshold is higher than that, as I am currently situated at 45 and do not have the option.

Then you do have the option. Maybe email us (hn@ycombinator.com) if you're still not seeing it?

Clarification: I have the flag option, but not the down arrow. What is the threshold for the down arrow appear?

Sorry for the miscommunication, I had assumed that both functions were enabled at the same threshold.