Why are his texts so formal?

SO there's this guy I'm talking to who I think really likes me(always text me first etc etc) and I like him too. on his Facebook he's always speaking in slang and like being so crazy and silly with his friends but like every time he texts me he speaks so formally like "good afternoon *insert my name*" or "how was your day" and he never like says just wassup or like any compliment to show that he likes me like that. why is this? The most like I guess sort of daring text he sent me was "I'm sorry to bother a pretty girl blah blah..." just because he said pretty. why is he so formal?
Why are his texts so formal?
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