Dear Joelv: I own two of its " big brothers " the AT ML/170-180 and owned the 150 and for what I remember I don't had that kind of trouble with the cartridge that btw is a good one.
About the " rubber parts " on cartridge's suspension over the years ( in many old MC and MM cartridges ) I never had troubles about and your is a NOS so I don't think that the trouble is in there but I can't be sure.
++++ " Old stylus maybe? " ++++, I don't think so either because your cartridge is new.
+++++ " The cartridge has about 2 hours of use so far " ++++
well you like Bri an or any one else can't think that 2-5 hours is enough time to make a precise judgement IMHO that cartridge or any other one needs more time.
Other subjects are to be sure about the right cartridge set up: VTA, Azymuth, VTF, overhang, load impedance, load capacitance, etc, etc. and this set up you can't do it till the cartridge suspension settle down ( about 20-30 hours ), your initial set up is only that a set up to start but not to evaluate the quality cartridge performance, so you need to have a little more patience about. Even after those 20-30 hours and with the right sey up you need to know if your tonearm is a good match for it, you can try here with different headshells and different wire headshells and og course with the tonearm damping and always could be a trouble with the quality on the phono stage, specially when we grow up/improve with a better cartridge.
Regards and enjoy the music.
Raul.