You may have a bit of crud holding the valve open just a bit. It shouldn't drain back. If it were me I'd buy a spare pump to keep on hand in case that one gives it up. If you haven't already done so it wouldn't hurt to put a filter between the tank and fuel pump.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.