The GVWR sticker is not a legal document, so you're not legally overweight. Now if your state registers the vehicle by GVWR and you have it registered as say a 7200 lb vehicle, then you're legally overweight. Otherwise...
Federal law controls maximum gross vehicle weights and axle loads on the Interstate System. Federal limits are 80,000 pounds gross vehicle weight, 20,000 pounds on a single axle, and 34,000 pounds on a tandem axle group
https://ops.fhwa.dot.gov/freight/policy/rpt_congress/truck_sw_laws/index.htm
Note, this is in the US.
