After that business with Sombra and his insane love of stairs, Twilight wonders if there is something amiss with her friends.
Because right now she's in Ponyville General and the last thing she remembers is a great tumble down some stairs. She doesn't remember what happened. Her memory has a block of time just gone and that terrifies her. And her friends just laugh off the questions that Twilight has about her accident like she is crazy. But she isn't crazy.
She will warn all ponies about the insidious and evil presence of stairs.