I think, it sounds normal to me. You may need to try letting the needle goes further down. How lower was your lower? But, I am not sure if there's any problem with your fuel gauge.
When my fuel warning light came on, after about 10miles, I went to the gas station, I bought about 15gal. of 220miles(purely city stop-and-go driving). Your mileage sounds right if you mix driving with interstates.
Try letting the "needle" go lower, if you "dare", and you may see the 'orange' warning light.
I asked myself to try as low as possible.....the most I only bought like 16.X gal. of premium. It's 18.5 gallons tank. I read someone bought a tank of gas about 18.X gal. - real low. However, I think that's not too good to try....I don't want to push my car while idling on uphills.