After digging a bit, I discovered my problem.

First, I dropped using Auth::check() and began using Auth::user(). When I called Auth::user(), I discovered I had set the incorrect value in my Eloquent model for what to return for getAuthIdentifier. I've since made it "return $this->attributes[$this->primaryKey]".

For those interested, this is my Eloquent model that I'm using for authentication. I highlighted the method.

http://laravel.io/bin/jQWXB#18-21

Some of the problems related to Auth::check() I believe was due to my use of dd() during debugging. I wasn't allowing the request to complete and thus wasn't writing back to my session appropriately. I'm not 100% certain on that, but I did see my session keys disappearing in Redis. That stopped happening once I returned a value instead of calling dd() and exiting the application.