isAuthenticated() returns false even after successful athentication

[sharp0111]

I'm following through the "Securing your React App with Auth0" tutorial's section, and the method isAuthenticated() of the "auth0Client" instance always returns "false" even after successful authentication (getting back the object with the user's information). Weird thing is it works when I set the value of "this.expiresAt" greater than the "new Date().getTime()". The reason is that "authResult.expiresIn" comes back as "null" value from the Auth0 server.