Nope. You’re not. But you should anyways. You’re never really “ready”.
Should it spell checked? Yes.
Should you debug first? Yes.
Should you check it over yourself? Yes.
Publish it. Change after you need to. The worst thing is to keep it to yourself.* (*except if it’s hate-filled… in that case, take a walk first)
PS — I appreciate that Medium uses this phrasing in its posting button as opposed to just a generic “POST” or “Submit”. It adds a human element. Maybe some additional testing, or even sentiment analysis on the draft, could change the wording to “Why not publish?” or “Thinking about publishing?”.