I have a crush on a guy, but he doesn't know me. So I dm him and he replied quickly but gives short answers, is he telling me to stop?

I dm him on my birthday, saying that his response would made my day. He did responded warmly, but when I ask other question he replied quickly but with very short answers. Is he feeling uncomfortable and giving me signs to stop? Should I be straightforward and say, "If u feel uncomfortable please do tell me, and I will stop"
I have a crush on a guy, but he doesn't know me. So I dm him and he replied quickly but gives short answers, is he telling me to stop?
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