It is your responsibility to ensure your wager is graded correctly, they didn't grade it wrong intentionally. Second, at 5Dimes you have a transaction history so it's not like it can be a "poof, I won a wager and it disappeared"- there's always an archive of your wagers that day or whatever, so don't trip out. If you're really worried, and you should do this anyway, take a screenshot of every wager after you place it.
You'll find that SBR offers this
tool for free.