It is extremely common. It happened to me about a month ago. Everytime I turned left, gas would leak out of my filler neck tube and onto my exhaust (very dangerous). There is a rubber seal that has gromets on it that connects your fuel tank to your fuel filler tube. It rips. Mine was ripped almost all of the way around. I bought the seal at Ford for exactly $19.09 after tax. I get it for cost since I'm a Ford Technician, so I don't know what the mark up is, I would imagine around $50 or so. Here's what to do...
-Make sure that there's not that much fuel in your tank. On the passenger side, there is a bracket that holds the filler tube and the gas tank. There is only 1 screw that holds it in, I think it's an 8mm. Take it out and slide that bracket out of the way.
-Some people take the filler neck out here, but you don't have to. It disconnects from the top where the gas cap is.
-There are 2 straps holding your gas tank. They are each held on by a 13mm bolt. The driver's side strap has the bolt in the front of the tank (closer to the front of the car) and the passenger side has it in the back of the tank (closer to the back of the car). Loosen them up and take the bolts out. When you do this, your tank is going to drop some, so make sure you have it supported somehow.
-Now slide the filler tube out of the tank. You may have to jerk the tank and tube away from each other to get it out.
-Once it's out, take the old rubber seal out of the tank. When going to put the new one in, make sure to lube it with grease. I used di-electric grease. Lube the hell out of the new seal and the filler tube. It makes it easier when installing them.
-Installing works the same. It only took me 10 minutes to do on a lift. If you're in the driveway, maybe about 20-30 minutes. Good luck and let me know how you made out...