I had a problem with the fuel gauge a couple of months ago. When I filled the gas tank up, the fuel gauge needle didn't go all the way to F - it stayed on 7/8 instead, and after I started driving, it went up a bit but didn't reach F. After I drove the car for three days, the needle finally went all the way up to F. That's when I took the car to the dealer and showed them the "before" and "after" pictures. They updated the instrument cluster software and told me to "keep an eye on it." So far, it's been working fine. I've also seen a similar story on Facebook, except that to fix the issue they had to replace the fuel tank sending unit at the dealership.