I Hate When People Disappear In The Middle Of A Conversation

What's the deal with people who randomly PM you, then disappear after an exchange of a few short messages? [removed by staff] just did this to me a few hours ago. So weird.
I have no issue with being PM'ed out of the blue, happy to chat to anyone, but is this a spam thing? Am I now supposed to be wondering where she's gone? Does she want me to follow her? I'm a bit slow on all this sort of tech-thing so would appreciate some thoughts from other people / experts here!


EDIT -
I'm adding some additional text below the original post here, just because there seems to be some confusion... This is a post asking whether a specific user (mentioned above) is a BOT or spam. This is not me thinking that this user is a real person who just left a conversation. If it were I wouldn't have posted it as I realise people can and will just suddenly leave conversations.
Thanks!