Ex calls me "dude"?

Hey guys! So me and my ex broke up a month ago after dating for 5 months (met families and friends). Today he texted after a month of silence (buf still liking my pics on social media) about something he wants back. I asked him when he needs it and he said in like a months time. Then i said "i ll take care of it" to which he answered with "cool thanks dude". This made me furious since I had told him many times in the relationship that I don't like the term "dude". So I said "no worries bro". Do you think he is doing it intentionally to annoy me? Why would a guy call his ex "dude"?
Ex calls me "dude"?
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