Question about using snapchat? Please help! Thanks!?

So I recently got a snapchat I only have one friend on it that's what he uses and asked me to make one so we could talk. My question is that sometimes I get an alert and it says he's typing and that he sent me something so I open it like today it was a little video of a wall and he said he hit his head on it. So I type back are you ok and then he types back WHAT? WHY? Oh cause I hit my head? Yea I'm ok. It just seemed like he didn't understand why I was asking him if he was alright but it's like ummm you just sent me that?..?... I guess what I'm curious about is if he's updating his story does it automatically get sent to me as a message even though he didn't actually send it to me specifically? I just don't want to answer to every little thing if he's not actually sending it to me that makes me feel like an idiot. Any help would be good on this one!