Right. If you have the remote lock/unlock (i.e., you have the fob), then there's only a key hole on the driver's door and the hatch. The passenger side doesn't have one.

My thought is that it may have been re-keyed. If that were the case, the key would still work in the ignition, but not in the door. Either one getting re-keyed would do this with the end result being that you're missing one of the (now 2) needed keys.

-G