Yeah my oath letter was very generic. No name, the field for application and client ID was blank. When the official handed it out to us, he had a stack of them and just passed them around so all the letters were identical.
Not sure why you had a different experience. This is the office on Glen Erin drive, correct? Maybe they have different days for different category applicants? cool497 and I were both Saturday morning people and those groups get fast tracked somehow?
Anyway if they told you an oath letter was coming in 4-8 weeks and you had a good interview, then I'm sure you will be fine, just need to be patient.