Oberservation after changing the 12v battery

yesterday , I changed out the 12v battery on my 2006 Prius with an Exide Edge FP-AGM51JIS bettery. Before the swap I had 4 pips on the gas tank reader , after the swap , it went up up 6 pips. Is this just another example on how not to trust the gas tank guage on the Prius ?
PS. I found on changing out the battery the hardest part was to put the screw back into place for the vent for the HV battery , its behind material up against the body of the car and just hard to get your hands in there , but with tips on how to do it from here I got everything done .