With the rate of gas explosion everywhere, it's best to know these basic things and stay safe. I've sincerely never checked my gas cylinder at home for any expiration date and that regular checkup you talked about that needs to be done every 5yrs hmmm, they need to tell people about that more often.
Imagine even the gas plants don't even tell you these things, all they do is fill your cylinder and that's it.
I doubt many of the gas plant employees know these basic things; as long as they give a commodity and receive their money, they are good.
And that's very bad