Snapchat automatically removes people?

Hey,

This is what happened: Someone added me, I accepted it and we messaged for about 10 minutes (just hello and stuff, nothing serious).

But after I was off for a bit and not on my phone, I wanted to see if he had answered and suddenly he was nowhere to be found.

Not in my chats or in my friends lists, just gone.

The question is, how does this happen? When someone is removed, you see an X next to their name, but it's completely gone.

Does anyone know what exactly happened there?

Thanks in advance:)