The Aroma of Propane

During our last outing we noticed the slight smell of propane coming from around the area of our stove. I checked with soapy water around the fittings and did not find any leaks (not to say there might have been one that I missed, but don't think so). Shortly after all this our tank ran out of propane and I went and had the tank refilled. After the refill the smell was gone, we no longer smelled propane. I then wondered as the tank runs really low would that (somehow) produce the propane aroma we noticed? Any thoughts? (we are using a 5 lb Flame King tank).
Thanks
John
Thanks
John