Why do you think he called me young lady?

Click on my gag photo.

This guy who was around 60 something years old who works at a store called me a young lady. Does that mean I look young or did he say it to be nice? And by the way I know I don't look like a teen or 21 years old so that's not what I'm indicating but maybe he assumed I was young? Even though I'm not a senior citizen either I'm just curious.
Why do you think he called me young lady?
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