Windows 8 and Bitlocker without TPM

Hi guys,
Over the weekend I upgraded my laptop to Windows 8; the main motivation for doing so was that Windows 8 seemed the cheapest way to get Bitlocker as I've started walking to and from work in the dark (with my work's laptop) and it seemed a sensible precaution to take.

Anyway, my laptop doesn't have TPM so I had to set up Bitlocker to work with a USB key. I've created the USB stick with the Bitlocker key on it however Windows doesn't seem to be requesting it upon start-up and only asks for my password.

I just want to check I'm not being a complete idiot. I was certain from every guide that I've read that without TPM support in the BIOS I would have to install this newly created USB stick AND type in my password whenever I started the computer. If this isn't the case then why did Windows insist on writing the key to a flash stick?

Is the encryption still secure when not using TPM or a USB Flash Drive in conjunction with my password?

Thanks for your help.

Chris