Yeah, I've had some screwy tanks lately, according to fuelly.com, and it has to do with early shut-offs more than anything.
My last 5 tanks: 53, 42, 44, 50, 54. It's worth noting that the average for that time span was about 48 mpg. Did I actually score a 50+ tankful during that time? Probably. I drove exceedingly carefully for one of those tanks and reached 443.4 miles on one tank (8.3 gallons to refuel), and I hadn't overfilled the tank the previous time, so in all likelihood I was getting about 51-52 mpg for that tank.