Would it bother you if someone responded with "okay" when you tell them something?

I play online with my friend often who I know in real life. Most of the time when I tell him something, he just responds with "okay...". Like, my sister was recently given a 2011 Subaru from a friend. I told my friend that, and he was just like "okay...". I'd say something "oh that's awesome" even if I didn't care, but he makes it blatantly obvious he doesn't care.

Would it bother you if someone responded with "okay" when you tell them something?
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