Weird JSON response when trying to log in.

Funny, I went to the login page, typed in my email and password, hit the login button and instead of being redirected to my page, a file called "highlights" was downloaded.

Below is the content of the file: (clearly JSON)

[{"link":"http://paulodelgado.com","title":"Hello World","response":200}]

I hit again the login button, and was successfully logged in, weird, only happened once.