Concern about my Gas Gauge.......

Ok, i know i have been asking questions alot about the gas gauge and i appreaciate the help. I just added this Fuel System cleaner to my car 2001 Pontiac Grand Prix SE 3.1 V6. All of a sudden i seem to be doing much better on gas. I have 143 miles on that tank of gas so far, and im on the notch right before 3/4 of a tank mark, it seems like the Gauge should be reading lower then 3/4 with 143 miles on a tank. or not?? just wandering, cause my mom was asking me.