Is my fuel gauge faulty?

Hi folks, this is my first post. Just got a 2012 Micra Acenta and filled it up with petrol and have done 55 miles since and the bars on the fuel gauge have not dropped at all. Is this normal? There are eight bars so I thought at least one would have dropped off after 50 miles. Any help is appreciated. Thanks.
I fill mine to the brim and the gauge does not move for ages on mine either. Obviously the sensor/float only goes so high and when you over fill it, it takes ages to drop. I do notice with mine that it's great on fuel according to the gauge until it gets to half a tank, then it seems to drop faster, but after working in a Nissan dealership, they all seem to do this, so I wouldn't worry. Just keep an eye on your mpg. Oh, and if you have the 1.2 3cylinder engine, clean your spark plugs every 3000miles, and replace them when they look worn. Don't leave them in for 40-60 thousand miles like it says, replace them every 20-30,000. It will run better.

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