Dealing with Apologies for Correct Gendering

How do you deal with someone apologizing for correctly gendering you and “correcting” themselves to the wrong gender? I’m ftm pre-t and work retail. Increasingly I’m able to pass from most angles so people will call me sir, but as soon as I turn around or speak they apologize and correct themselves to ma’am. I’m already incredibly awkward about correcting people when they misgender me, and it feels even weirder when they get it right the first time but think they had it wrong. I’ve either not been saying anything or saying something like “no, you had it right the first time,” but at best they don’t react at all and at worst they just look confused. Anyone else have this problem? What do you do?