Here is a good post to reference for deficiencies
To better assist could you provide details such as
soil used
Nutrients used
Etc
Over all they look great and yea I see what you mean with the gold leaf but don’t think it’s iron issue.
I had not heard of torching before so could be.
If not and just keep an eye on it daily and it will either get better or worse…
Soil ph out of range can cause issues or she is starting to need more nutrients maybe than the others.
If so you’ll want to adjust her feed up a bit more than the others.
As they go into flower they will want more Phosphorus and Potassium and less Nitrogen so adjust what you are feeding accordingly.