Mine does the same thing. I took it back to the dealer and they replaced the entire pump / sending unit assembly under warranty but I don't know that it actually made a difference. I haven't ridden much over these winter months. But it doesn't seem right because a couple years ago I rented a 570 and it seemed like it would go half a day before you'd see the first bar drop on the gauge.It does not seem to be very linear. I was down to 2 bars out of 8 and I was only able to put in 3.5 gallons.
What have you experienced?