Gas Gauge (warm weather)

2008 Prius Pkg 6 at about 160k miles and we are the original owners. Suddenly we are having a few issues.

First is the gas gage issue. I've read several of the threads and they all seem to point to the bladder and cold weather. We live in the south and this has been happening Spring and Summer (all year). Just now 88 degrees outside making a two-mile drive to the grocery store it went from 9 squares to 4 to 3 then 1. If he stopped to get gas like all the other times it may take 1 to 3 gallons only.

So not the cold bladder issue, maybe gas gage? Thoughts?

I said issues, plural, going to an AC thread next...