Does it look like this?:
http://www.ebay.com/itm/FAULHABER-DC-12V-Motor-2342L012CR-Gear-64-1-Encoder-12CPR-free-ship-/130585677299
The 12CPR likely indicates it's using a pair of hall sensors and a multipole disk magnet for the encoder.
Which would be 64:1 x 12 CPR = 768 CPR at the shaft. With the gear head that is a pretty good count.
Edit: Just saw the back of the motor, it's slotted disk and opto, not multipole magnetic and hall...