I had this happen once to me on my 07 X5 4.8 two weeks ago. The differerence this time was when comming out from the station I made a right turn and accelerated hard to get to traffic speed and because it is fun. The fuel guage showed 1/2 tank but over time the needle as well as the miles to empty readjusted to full. It took maybe 20 minutes.

I just figured the aggressive start messed up the float for a bit but it does work it's way back to normal.