there was gas on the filter.
depends on how much gas.
Your dirty air filter could cause the engine to draw more fuel then usually needed.
See,the motor is really just a pump. It's going to pump when running and it's designed to draw a certain amount of air and a certain amount of fuel.
What will it do when it can't draw that certain amount of air? It's going to draw more fuel until you replace that air filter.
One other reason for fuel on the filter is a stuck needle in the bowl assembly of the carb. Highly unlikely though.