I noticed that same issue a while back. After checking the vent controls, fluid levels, I decided to change my thermostat bc of a thermostatic fault error and it solved my heating problem.
'11 328i (sold)
'07 Audi A8
'03 745Li (sold)
'03 Acura TL-S (sold)
'15 Toyota Sienna Limited Premium w/Dynamic Cruise
'15 Infiniti Q50 Premium w/NAV & 19'' Wheels