Someone downvoted and commented on an answer I posted. I thought I better edit it. I was logged in. There was no edit link and it re-appeared a few hours later. That was very strange behaviour.
The loss of the edit link could happen if there was another user actively editing the answer at the time.
The link would reappear once they finished or abandoned the edit.
However, if someone proposed an edit, you should have been given an inbox message offering you the chance to approve or reject it.
So, I can't answer definitively, but I would suggest this is what happened.