A missing gas leak

I picked up the faint smell of LP gas in my kitchen.  I figured the gas fitting on my kitchen range had loosened. We live a mile or so from a RR track, and sometimes I can feel the house shake. Anyway, by coincidence, my stove ran out of gas, so I switched tanks.   Now there is no gas smell inside the house.  Yes, the tanks are outside and the stove is inside. The windows near the range and tanks were closed.   What is going on?

John I can't explain for sure why, but I've lived with propane all my life.
They always develop a slight smell when the tank is almost empty.
Happens every time... hey do you smell propane ??? Why yes I kinda do...
Go check the tank (250 gallon) it will be  10% or less.

Now you may not like this method but... to find a small propane leak I use a match!
No they don't explode.  
You will get a small flame if you have a leak, just blow out the flame and tighten the fitting.

The soapy water method is worthless unless you have a major leak.

Thanks for the reply Thomas.  I switched from electric to LP maybe 5 years ago.  I have had faint LP odors before .... this is the first time I have noticed it in connection with an empty tank, but I am not always the most observant person.   I have a gas alarm near the range, and it was not going off. Like I said, the odor was faint ....but it was there...for several days.  

I use 100 pound tanks.  I keep a few around for multiple purposes.  They are more expensive to refill, but I can move them to where they are needed with relative ease .... and I can get them refilled by tossing them in the back of the truck.

"They always develop a slight smell when the tank is almost empty."

howdy,
This is meant to happen. I think it's a safety thing. Propane guy told me. Has garlic like smell? = low on propane.

randal cranor wrote:"They always develop a slight smell when the tank is almost empty."

howdy,
This is meant to happen. I think it's a safety thing. Propane guy told me. Has garlic like smell? = low on propane.

This rings a bell. I was going to say I think I heard something like this.

My understanding is that propane is naturally odorless. They add the smell (made from eggs) to make leaks easier to detect. I've always been told that. I've surmised that the stuff they add is heavier than the propane, so tries to settle out, hence the propane near the bottom of the tank has more smell.

LPG is naturally odourless. To avoid harm it is added with the smell of rotten eggs.
If you don't feel any smell, I think there is some issue with your propane tank. Too much air, water or rust in the propane tank may be the reason.
Also, check that the propane tank has no leakage. Because, if your tank has any leakage, then the soil may diffuse the smell.
So, ensure that your tank is in proper condition.