Upon reading your article entitled "Should wives call their husbands "lord?"", I find it quite impossible that this refers to simply an inward confession. In I Peter 3:6, the context of Sara calling Abraham "lord" doesn't have anything to do with the appearance of the angelic announcement that she would have a son in her old age, as found in Genesis 18:9-15. But, rather, the context is stated in the wording "Even as Sara obeyed Abraham, calling him lord. This must mean that she actually addressed Abraham in this way during the course of their everyday living domestic marriage relationship. 'Obeyed' means 'to hear under; listen attentively.' I do not believe that I Peter 3:6 would be fulfilled without Sara actually addressing Abraham as 'lord.' If she never called him 'lord', it is meaningless for Peter to say that she did.
Regardless of your objection, Peter makes mention of Sarah calling Abraham "lord." "For in this way in former times the holy women also, who hoped in God, used to adorn themselves, being submissive to their own husbands; just as Sarah obeyed Abraham, calling him lord, and you have become her children if you do what is right without being frightened by any fear" (I Peter 3:5-6). There is only one place where this is recorded: "Sarah laughed to herself, saying, 'After I have become old, shall I have pleasure, my lord being old also?'" (Genesis 18:12). Peter makes a significant point about submission from a small fact that could easily be overlooked.
The fact that Sarah thought of her husband as her lord, tells us more than a mention of her calling him "lord" verbally. We know that people's words don't always match their thoughts. But here we have Sarah's thoughts and so we know that they govern how she behaved.
Peter's point is about submission, not about calling husbands "lord." Sarah's unvocalized consideration of her husband sets the example of how women should be submissive to their husbands. It isn't just outward obedience, but a submission born first in the heart. When a wife reaches that point in her own thoughts, regardless of how she might verbally express herself, she has become a daughter of Sarah as she submits to her husband.