My '06 does that. I can tell when the pump is about to kick off as the pitch goes up, so it's kind of handy in a way. hehe
Some owners say that in cold weather it will splash a bunch of gasoline back out the filler when it does it.
Seems to mostly happen in the frozen north in cold weather when the tank has been down near "empty".
All it is is the release of air/gas vapor pressure from the tank.
When the gas goes in, the air/gas vapor has to come out somewhere.
Nissan has closed up and restricted the normal wide opening at the filler so there is only a VERY small gap between the pump nozzle and the filler throat.
There is supposed to be a small vent through piping to the charcoal filter to capture the gas vapor while you are filling the tank, but that is either too restricted or a valve fails to open that vent path.
So the air and gas vapor build up in the tank, and occasionally it throws up like a kid with a stomach problem.
The rest of the time it just whistles as the air and gas vapor come out the filler throat through the narrow opening around the pump nozzle.
