Don't worry! it happens naturally because it's the way people speak in small conversations, and in that context perfectly ok.
The unnatural part is us trying to steer this large/public conversation away from the standards of small/private conversation, which is basically impossible but also a must, if HN isn't to self-destruct.
Edit: there's an additional twist, too, which is that HN's form factor feels like a smaller and more intimate conversation than it really is. That's great in many ways! But it obscures the fact that when people post here, they're really broadcasting to a large audience.