You have an early (non public) unit. I don't have a vibration motor in mine either.
I haven't tested using my preproduction unit, I was using my Kickstarter special edition. Weirdly enough, after trying it again, it now DOES vibrate, but only in the SDL 2.0 version. (Actually, I'm not sure if I just neglected to try it on the SDL 2.0 version before or if something actually changed.)
Also, I get the same issue on my unit everyone else is having, where the vibration doesn't stop when the buttons are released.
So to amend my previous notes:
White Kickstarter Special Edition Zero:
- No vibration in SDL 1.2 version
- Vibration that continues after buttons are released in the SDL 2.0 version