Two new problems

[Rock]

Noticed last night heater ran way longer than normal. Just got the water heater fixed and now this. Heater ducts fine but heater is blowing warm and not hot air like it should. Running the heater I turned stove burners full, fridge on propane that all were fine with heater. I was trying to see if propane reg that I recently replaced was the problem ( it is the recalled one but my serial number is not in recall). Like I said ducts are all good I took the wall down at tonight’s stop. All I can figure is a bad hose or that new regulator. I have two electric heaters and the fireplace so not an emergency issue. Any ideas what else could cause this. The heater has worked fine until today.