Weird sloshing noise

I just bought a brand new 2010 chevy camero about a month ago and love it!!!But just today I noticed a weird sloshing sound coming from the fuel tank area when the car is pushed back and forth with your hands. It sounds like you are shaking a water bottle around…what is wrong with the car??? I actually noticed it first because I thought my windshield wiper fluid bottle in my truck was moving around, but then I took out the bottle and gave the car a good shake and heard the noise coming from the fuel tank area? Please offer any opinion!!

Look at the fuel gauge. Do you have 3/4 tank?

yeah it’s 3/4 full

but i have never heard that noise before since i have owned the car