I had the same thing happen to me, the charge that appeared was 20% more than the charge signed for.
But the actual amount of money taken out, and the number that the charge read after it was fully processed by the bank, was the number I'd signed for.
I'm still not sure what that was all about... happened in DC.
It's government pressure. The IRS "imputes" a certain amount of tip, based on a witer's income, so the restaurant sometimes includes it above a certain amount so they (and their servers) can't be accused of tax evasion.
Which is precisely why I NEVER include a tip in any credit card charge at a restaurant. I jsut leave it on the table.