2003 Audi A4 over pressure in gas tank when pumping

2003 audi A4 1.8T Quattro. My car has been recently serviced and is running just fine, but for two weeks now when I go get gas it creates an over pressure situation in the gas tank (nothing when I take the cap off before pumping). The pump stops after about.3 gallons and when I take it out you can here all of the pressure hissing out. Then it's good for another tiny bit of gas- same problem on repeat. I have tried multiple gas stations but no difference. What's going on?