Have an 05s 150k miles. Here in the past few days I have had a fuel smell inside the car. I can't smell anything outside. No leaks from what I can see. I am guessing might have something to do with the fuel filter, since you change it under the passenger seat

 

I had that happen once on a CRX I owned. The problem was I hadn't seated the gas cap properly. Check to make sure it's 'clicked'.

 

Check gas cap, did you overflow the gas tank or top it off too much and flooded the charcoal canister in the back near the fuel tank.

Did you change the fuel filter recently ?

Did someone spill gas at the station and you accidentally walked over it and then got a little on the floor mats, does not take much.

 

Check the gasket for the fuel pump under the rear seat. Also, definitely make sure you don't have a fuel leak somewhere. The vent valve has been known to give some trouble and cause the cabin of the vehicle to smell like fuel. Some info HERE.