Assuming you mean you traveled 258.5 miles on a 99% charge, that's actually pretty normal. That's about 282Wh/mi (77.8kWh/258.5mi*0.99*0.955*0.99), as displayed (assuming you did this mileage continuously, which you probably didn't, so your actual consumption while driving was probably considerably lower).
Likely nothing wrong with your battery. Remember the 353 rated miles is only loosely correlated with distance. It's a representation of energy, not distance.
If you want to do 353 miles, do it all in one shot, and drive slow enough that your average consumption shows ~209Wh/mi (and do it soon, before your battery loses a small amount of capacity). If you start to exceed 209Wh/mi, drive more slowly (probably something like 40mph will do it if you have climate control off - so about 8-9 continuous hours in the car).
EDIT: (Deleted the comment about
@Kimmi, since the poster was referencing rated miles. Hence the calculation worked out to be exactly the discharge constant.)