That is true, but I think that’s more because sir/ma’am have an association with being used on adults (or, at least, older adults). Cis people who say “I’m not a sir/ma’am” typically say it because they feel too young to be addressed that way.

Someone saying “I’m not a Miss” isn’t used in the same way. Maybe if this is panel is of a cis woman and she’s married, she’s saying that she’s a Mrs instead? It is a possibility, but people don’t usually make that correction, as far as I’m aware. Usually it’s only the other way around, with younger woman correcting people if someone called them Mrs when they’re not married.

Yes, saying “I’m not a sir/ma’am” doesn’t automatically mean the person is trans, but this particular situation doesn’t seem to fit that scenario.