Not bloody likely
The Tunguska blast has been estimated as equivalent to 9 megatons. That's the amount of force released by detonating 9 million tons of TNT. It's very doubtful that you could get that kind of explosion from natural gas. You'd first have to have millions of tons of gas released and then detonated instantly. The blast pattern on the trees would be different as well. The trees around the epicenter of the Tunguska blast all radiate outwards from the center. You wouldn't get that kind of pattern from a massive gas explosion.