iMessage turning on

Is it possible for iMessage to turn itself on?

I received a MacBook from a boyfriend over the summer and used iMessage on my laptop back on. However, since then, I haven't used it.

So I'm sitting in bed and all of a sudden I get a notification that my iMessage has logged in on my laptop and then another notification that it has logged in with my phone number......

but my laptop isn't being used and I don't think it's even on? Is that possible?