Can't Access WP Admin without "www"

Hey friends!

I just activated the "Network" feature on my standalone Wordpress site using subdomains. I also included noblogredirect due to some issues I was having when typing thinktaiwan.com (it was going to sign up page) But now, I cannot access my WP Admin panel without typing "www" in front of thinktaiwan.com

Is this by default? It is not a big deal I suppose unless there is something wrong with my set up. Anyone have any idea? Thanks so much!

Mike