You shouldn't have to? You can't prove what would've happened. You could've just as easily of won, but you didn't so you're just looking for this excuse to work, and it doesn't look like it is. Just cut your loses and move on.
That is not the point. I lost not knowing the error had affected my seed.
Primedice website says how important the client seed is in determining the outcome of rolls so I would be crazy to just 'cut my loses and move on' because this very important seed was changed by primedice during my betting.
If anything, this kind of complaint will give primedice encouragement to fix the errors and make the game as fair as possible.