Welcome to JA.
It would not melt it in 100 miles. By the time the exhaust gets back to the tail pipe where the tank is which is in the very back of the vehicle it is not really hot enough to do so. Especially while driving and the air blowing on it. You need to see if the exhaust and the hole line up or are close to each other. There should have been a recall done on this which an updated tank installed. They were having issues with gas leaking out of the vents on the top of the tank. So if that is the case then you can have the recall done on it and the tank replaced. You can call your local dealer and give them the VIN and they can look it up for you to see if the recall is still open on your vehicle. Thanks Daniel