Went camping Labor day weekend, filled up (1/2 tank) and began to notice the fuel gauge seemed to be vibrating? Doesn't hold still like rest of gauges, but appears to move rapidly 1/16 to 1/8 inch to either side of actual fuel reading (moves so fast to almost appear to be a blur). Gauge still reads accurate. Could bad gas be a cause of this? Always think worst case and hope fuel pump not starting to go bad. Any help would be appreciated.