The 30 mins/mo. is a service interval recommendation. The mfg knows that a month interval between operating is going to keep the machine operating better. There is no problem operating the generator for shorter durations.
Is this by any chance, an Onan generator? Cummins/Onan is real specific about schedule of operating intervals.
A good way of thinking about generator maintenance and service is to mentally multiply usage by 100's and compare that to vehicle service. For example: A generator operated for 100 hrs would need the same typical services for a vehicle operated for 10,000 miles. Most folks are more conversant with vehicle maintenance than small engine service.