Seems like I always have more questions than answers

I am assuming the whole house generator is not operating right now?

Is this your tank or a tank leased from an LP company?

When was it last filled and how full is it?

Here is why I am asking all the questions.   If the generator is not running it should have no effect on anything.  About the only things I can think of that would cause and LP tank to make noise is a relief valve opening, thermal differentials, or tank failure.  Since the tank hasn't gone boom or started leaking I will assume that is not it.  Since there is not a big draw on it (it would take one BIG generator to make that kind of load) I will assume it is not being chilled by vapor withdraw.  That leaves it either being too full or the relief valve failing ... or working like it should.  First thing in the morning, or maybe tonight with a flashlight, check the dial and see how full it is.  Most likely it is a percentage gauge

You'll like this next suggestion.  Take your pliers or a Crescent wrench and tap the side of the gauge (not the dial, but the gauge itself) a couple times to make sure it didn't stick.  Here is what you are tapping on ... or similar

It may have 4 bolts instead of screwing in.

There are a few out there with big dials that read in gallons, but they are not common.

If it is over 85% you need to call your LP supplier and ask why.

OH! And about the leak., here is why I asked what it was and what you did.  From http://www.propane101.com/safetyreliefvalve.htm

Pictured left is a relief valve that was apparently leaking. Instead of calling the propane company to replace the valve, the customer decided to fix the problem himself. Using a soldering iron, he soldered the leak until it stopped leaking. In the process of "repairing" the leak, the customer completely sealed the relief valve in a closed position placing himself and his family in a very dangerous situation.

 

In this type of situation, a relief valve that is sealed shut will not allow the tank to vent excess pressure if it is overfilled or the pressure inside the tank exceeds the working pressure of the container. In a case where the tank is unable to vent to the outside, the tank is subject to rupturing causing more harm and damage than money saved by trying to fix it yourself. Let the propane company or LPG professional handle any problems with thesafety relief valve.

 

By the way, http://www.propane101.com is a great site for LP info