weejonnie, on 2017-February-23, 09:51, said:
In cases of MI, the TD may consider offering the leader his last call back.
I assumed the only irregularity was the wrong defender making a face-down lead. If there was also MI, that's a totally different issue.
In practice, players also rarely call the TD when someone corrects a misexplanation at the end of the auction (unless the NOS think they were damaged). That's a more serious problem. Of all the common self-rulings, I think rectifying an unfaced opening lead out of turn is the least serious.