Same here, and I guess it made us jump because they did not build the scene up for a jump-scare. It was perfectly mixed into the scene so you would not see it coming.

HAHAH! Don't be. It's good no joke

It is quite scary, trust me when I say this, most of the scary parts, you can easily miss as they happen in the background without any indication, no joke, very rarely do horror movies focus on actually letting the viewer of the film, pick up on the scary things, as usually in horror films, everything is spoon fed so you won´t miss anything.