Is it flirting when a guy calls a girl ma'am?

Typically, I never had anyone called me that before except my previous clients at work lol. Recently, I noticed a friend who is my age kept referring me as "ma'am" on texts even though I already told him to not called me that lol. But he still does it... Now, it's making me wonder is this considered flirting?

Examples of his texts:
"Say when ma'am..."

"I'm an open book ma'am, ask and you shall receive"

Is it flirting when a guy calls a girl ma'am?
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