I've had that hapen when I call the bank to see what the last transactions were and the amount from any restaurant I've been at is off a few dollars. What someone told me was that they'll run the card through for the amount they think they'll get tipped to make sure it is approved for that amount. Then go in at the end of the night or next day and adjust it to the correct amount. I'd call your bank and see if the amount changed over the last couple days. If it doesn't adjust, I'd file a dispute.
Good Luck! You wouldn't believe what I had to go through when my purse got stolen.