Just got an update. So I was right after all. My service advisor called me back and told me that the fuel filter is supposed to be replaced at every second oil change
So make sure you all get your fuel and intake air filter replaced every second oil change. If they refuse, refer them to the attached file. It states this on page 11;
Emission Control Maintenance
Schedule
The maintenance schedule as shown is required
for the proper functioning of the emission control
systems for optimum vehicle performance and
fuel economy.
Basic Engine
Engine oil As specified by CBS
Engine oil filter As specified by CBS
Fuel System
Air filter Replace at every 2nd
Engine Oil Service
Air filter (Z4 only) As specified by CBS
Fuel filter (335d only) At every 2nd engine oil
change