Is it a discrepancy in your favor? Maybe you unlocked your deposit bonus, or got the $25 bonus from signing up through CardsChat or something?
Do you use PokerTracker or Hold'em Manager?
First have PS save your hand history, so you can go back on your own for reference:
Poker Stars Lobby -> Options -> Instant hand history options -> check "Save my hand history"
Next, request your tournament history for the past 99 tournaments (or whatever). Then all of your results will be emailed to you.
Poker Stars Lobby -> Requests -> Tournament History...
You can compare those results to your own.
If I were you and I was keeping my own records with a spreadsheet, I'd take this as an opportunity to try PokerTracker.
First, I'd email email@example.com
and request my *complete* hand history (I got mine in a few days, but my friend's took a couple weeks). They send you a link where you can download a variety of ZIP files that have the data.
Then I'd download the trial version of PokerTracker and import all that data.
have PokerTracker import all your results too. Then compare that number to what's in your account.