What does it mean when a guy mimics your sayings/phrases?

This guy at my job seems to adopt a lot of my funny sayings/phrases. Like i'll say something and the next day, he'll say the same thing in a conversation! Its strange because none of the other guys at my job do it except for this one other guy (at a lesser degree). I dont think he does it to mock me because he's pretty nice overall. Could it mean he likes me? We're both 18 by the way. Also when we have a great conversation, moments later he'll get kinda cold towards me and not talk very much then when i get the hint and back off, he'll get all warm again. What could that mean?
What does it mean when a guy mimics your sayings/phrases?
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